dear friends and participants of the 2010 mr angio club meeting

MR-Angioclub Seoul, South Korea 2010 1

Dear friends and participants of the 2010 MR Angio Club Meeting

It is with great pleasure that we welcome everyone to St Mary’s Hospital in Seoul, Korea for the 22nd International MR Angiography Conference. Since being founded by a team lead by Dr. Jim Potchen in 1989, the MR Angio Club has spanned the globe from North America to Europe to Asia spreading the knowledge of MR Angiography around the world fostering new ideas and helping young investigators establish their MR careers. The Local Organizing Team led by Tae-Sub Chung is excited about the excellent quality of the greater than 100 abstracts submitted to the 22nd Annual Angiography meeting. Both the oral presentations and the electronic poster section should provide very stimulating discussions typical of the MRA Club meetings. We are also proud to announce a Student Poster Award, a dozen student stipends and a new Potchen Award as part of this year’s meeting. St. Mary’s Catholic Hospital Reserarch Auditorium will be an excellent facility for our scientific program. The Local Organizing Team has also arranged an exciting social evening program to highlight the culture and Splendor of Korea.

We are grateful for the ongoing support of our corporate sponsors who continue to support such stimulating meetings. The sponsors are listed elsewhere in this program an on the meeting homepage. We are also indebted to the London, Ontario Team including Janette Wallace, Johanne Guillemette, and Jade Orkin-Fenster. We hope you enjoy the 22nd International MR Angiography Conference and welcome to Seoul. Organizing Team Tae-Sub Chung.......................................................Local Organizing Committee

Chairperson

Seong Eun Kim.......................................................Scientific Committee Chairperson

Martin Prince...........................................................President MRA Club


Conference Organization President President Elect Executive Board

Secretariat

Martin Prince Graham Wright Arlene Sierra

Past Presidents Executive Board

James Potchen

Georg Bongartz

James E. Siebert

Paolo Pavone

Dennis L. Parker

Jorg F. Debatin

John Huston

E. Kent Yucel

Frank R. Korosec

David Saloner

James F. M. Meaney

Brian K. Rutt

Debiao Li

Stephen J. Riederer

J. Kevin DeMarco

Georg Bongartz

Kevin DeMarco

Phillipe Douek

Charles Dumoulin

Christoph Herborn

John Huston

Frank R. Korosec

Gerhard Laub

Debiao Li

James F.M. Meaney

Hitoshi Miki

Charles Mistretta

Dennis L. Parker

James Potchen

Martin Prince

Stephen J. Riederer

Brian Rutt

Kazuhiko Sadamoto

David Saloner

Klaus Scheffler

Stefan Schoenberg

James E. Siebert

Graham Wright

Local Organizing Committee Conference Team Webmaster

Tae-Sub Chung Kook Jin Ahn

Dong-Hyun Kim Jong Min Lee

Chang Hyun Oh Bum Soo Kim

Chang Ki Kang Byoung-Wook Choi

Janette Wallace, Manager Johanne Guillemette,

Coordinator Jade Orkin-Fenster, Coordinator

Kevin Henley

Scientific Program Registration Service Convention PM Director

Seong-Eun Kim Dong-Hyun Kim

Martin Prince

www.registrationassistant.com

Young Chang


The 2010 MR Angio Conference Timetable

Wednesday (Oct 6th)

07:30 – 08:45 Registration

08:45 – 10:00 Opening Session

10:00 – 10:30 Coffee Break

10:30 – 11:42 Contrast Agents

11:42 – 13:00 Lunch

13:00 – 14:54 Pulmonary MRA, Venous Imaging, hand MRA, CAIN


15:12 – 17:00 Flow visualization

Thursday (Oct 7th)

08:00 – 09:24 Intracranial Aneurysm


09:54 – 11:44 Peripheral MRA

11:44 – 13:00 Lunch

13:00 – 13:36 Interventional MR

13:36 – 15:24 New MRA techniques


15:44 – 17:10 Compressed sensing and HYPR

Friday (Oct 8th)

08:00 – 09:36 Coronary MRA and Cardiac


10:06 – 11:56 Abdominal MRA

11:56 – 13:26 Lunch

13:26 – 14:50 Intra-cerebral MRA, AVM


15:10 – 17:00 Neck MRA, Vessel Wall Imaging


MR Angio 2010 Club appreciates the generous support of the following sponsors: PLATINUM

GOLD

SILVER


LOCAL SPONSORS

* THIS BOOK WAS PRINTED WITH KOREAN MEDICAL ASSOCIATION FUNDING.


Floor Plan & Exhibition Booths


1. PROMOTIONAL DESK 2. BANFF MR ANGIO 2011 3.

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11. 4 & 5. 12. 6. 13. 7. 14.

8. 15.


General Information Venue Seoul St. Mary’s Hospital Address: #505, Banpo-dong, Seocho-gu, Seoul 137-701, Korea Registration Registration desk will be located in the foyer of Auditorium in Main Building of St. Mary’s Hospital.

Operation Time - Oct. 5 3 pm – 4:30 pm - Oct. 6~8 7:30 am – 4:00 pm

Coffee Breaks & Lunches Snacks and drinks will be provided on the foyer and exhibition room. Lunches will be held at the Dynasty Hall (B1) in Seoul Palace Hotel. Internet Access Wireless internet is available during the conference period. Speakers All speakers are requested to drop by the preview room (Auditorium Foyer) and upload their presentation file at least 90 minutes before the start of the session of their presentation. Our staff will assist you to preview and upload the file. Your presentation file will be deleted from the server after your talk and thus not made accessible to third parties. E-Posters Poster presenters are requested to upload their files in the PC for e-posters located in the exhibition room by 10 am on October 6.


Spousal Program

Wednesday (Oct 6th)

07:45 – 15:30 Demilitarized Zone Tour

Bus leaves Marriott Hotel at 07:45

Tour of Imjingak, The 3rd Tunnel, Dora Observatory, Dorasan Station

Lunch at Deungmaru restaurant

Thursday (Oct 7th)

09:00 – 16:00 Ganghwado Island


Tour of Gaghwa History Museum Jeondeungsa Temple, Goindol Rocks

Lunch at local restaurant

Friday (Oct 8th)

09:00 – 16:00 Seoul City Tour


Tour of Changdeokgung Palace, Insadong Alley, N Seoul Tower, National Museum of Korea

Lunch at Ocean Seafood restaurant


Social Program

Tuesday (Oct 5th)

18:00 – 20:00 Welcome Reception

JW Marriott Hotel

Meeting Room 1, 3rd Floor

Wednesday (Oct 6th)

18:30 – 21:00 Grand Banquet

JW Marriott Hotel

Grand Ballroom, 5th Floor

Thursday (Oct 7th)

17:30 – 21:30 Gala Dinner

Gail Art Museum

Bus leaves St. Mary’s Hospital at 17:30

Friday (Oct 8th)

17:30 – 21:30 Farewell Dinner

Samwon Garden

Bus leaves St. Mary’s Hospital at 17:30


Wednesday, Oct 6th

08:45 – 10:00 Opening Session

8:45 President opening remarks Martin Prince

8:50 President, St. Mary Hospital Young Seon Hong

9:00 President, Korean Society of Radiology Dong-Ik Kim

9:05 Local Organizing Committee Tae-Sub Chung

9:10 Radiation Controversy Jeff Brown

9:20 Latest MRA Advances Tom Foo

9:30 Contrast MRA Advances Stefan Rhuem

9:40 Non-contrast MRA overview Vivian Lee

9:50 MRA Future Directions Panel Discussion Martin Prince


10:30 – 11:42 Session 1 Contrast Agents

Session Chairs : Tim Leiner, Jeff Brown 10:30 Emanuel Kanal

1.1 Decrease in acute adverse reactions to gadobenate dimeglumine

10:42 Zhitong Zou 1.2 Comparison of Blood-Pool and Extracellular Contrast Agents on MRA of Abdominal Perforator Flap Arteries

10:54 Bas Versluis 1.3 DCE MRI with Gadofosveset in Peripheral Arterial Disease: Assessment of the Hyperemic Microvascular blood volume

11:06 G. Hahn

1.4 Safety of 1.0M macrocyclic gadobutrol in MR angiography in pediatric patients – A German multicenter analysis

11:18 Rubin Sheng

1.5 Low Dose (0.1 mmol/kg) Gadodiamide-Enhanced Magnetic Resonance Angiography (MRA) for Detection of Renal Artery or Aortoiliac Occlusive Disease: Results of Two Multicenter, Prospective International Trials


11:30 Thorsten Bley 1.6 High resolution vessel wall imaging in giant cell arteritis: 7 years experience

11:42 – 13:00 Lunch

13:00 – 14:54 Session 2 Pulmonary MRA, Venous Imaging, hand MRA, CAIN

Session Chairs : Jim Meaney, Tim Leiner

Pulmonary MRA

13:00 Jeff Brown for Pam Woodard 2.1 Signal quality of single dose gadobenate dimeglumine pulmonary MRA examinations exceeds quality of MRA performed with double dose standard gadolinium-based agent

13:10 Kana Fujikura 2.2 Features of COPD on time-resolved Pulmonary MRA

13:20 Kang Wang 2.3 Dynamic Pulmonary Perfusion Imaging using Interleaved Variable Density Sampling, Parallel Imaging and Cartesian HYPR Reconstruction

13:30 Discussion of pulmonary MRA

Venous Imaging

13:40 Winfried A. Willinek 2.4 Preoperative mapping of autogenous saphenous veins as an imaging adjunct to peripheral MR angiography in patients with PAOD and femorodistal bypass grafting: Prospective comparison with ultrasound and intraoperative findings

13:50 Tim Leiner

2.5 Evaluation of the long-term consequences of deep venous thrombosis using bloodpool enhanced MRI

14:00 Guido M. Kukuk 2.6 Prevalence of deep venous thrombosis as detected by magnetic resonance thrombus imaging with a blood pool contrast agent in patients with suspected peripheral arterial disease

14:10

Manuela Aschauer 2.7 Imaging of thromboembolic disease with MRA/MRV


14:20 Discussion of Venous Imaging

14:30 Zhaoyang Fan 2.8 Noncontrast MRA of the hand using mutli-directional flow-sensitive dephasing preparation

14:42 Richard Frayne 2.9 The Canadian Atherosclerosis Imaging Network – A Frame Work for Pan-Canadian, Multi-modality Vascular Imaging Studies


15:12 – 17:00 Session 3 Flow visualization

Session Chairs : Michael Markl, Kevin Johnson

15:12 Yasuo Takehara 3.1 Hemodynamic Assessment of Abdominal Aortic Aneurysm with Use of Three Dimensional Cine Phase Contrast Image and Flow Analysis Application

15:22 Marcello Cadioli

3.2 7D PC MRI to study Helical Blood Flow in the Human Aorta

15:32 Michael Markl 3.3 4D Flow and Plaque Imaging in the Descending Aorta: Stroke Risk by Retrograde Embolization

15:42 Jelena Bock 3.4 4D Pressure Difference Mapping in the Aorta

15:52 Discussion of aorta flow visulization

16:02 Aurélien F. Stalder 3.5 Analysis of swirling flow patterns using 4D flow-sensitive MRI

16:12 Kevin Johnson 3.6 Hemodynamic features of the cerebral dural sinuses demonstrated by PC VIPR MRV

16:22 Ramona Lorenz

3.7 Correction methods for streamline visualization in the aorta and the superior sagittal sinus of healthy volunteers

16:32 Discussion for Intracerebral flow visualization

16:42 Poster Viewing


Thursday, Oct 7th

08:00 – 09:24 Session 4 Intracranial Aneurysm

Session Chairs : John Huston, David Saloner

Intracranial Aneurysm

08:00 Franz Ebner 4.1 How accurate are CE and TOF MRA at high field strengh (3.0.T) in assessing morphology and size of reperfusion of cerebral aneurysms after endovascular coiling

08:10 John Huston 4.2 New Natural History Findings Utilizing MRA for the Study of Intracranial Aneurysms

08:20 Karl Diedrich 4.3 Stability of vascular centerlines and peak tortuosity measurements

08:30 Dong-Hyun Kim 4.4 Accurate aneurysm morphometry using variable view angle tilting acquisition and super-resolution reconstruction

08:40 Discussion for Intracranial Aneurysm

Morphology of intracranial aneurysms

08:48 David Saloner 4.5 Velocity Fields In Intracranial Aneurysms

08:58 Haruo Isoda 4.6 Magnetic resonance fluid dynamics of growing intracranial aneurysms

09:08 Steven Kecskemeti 4.7 Accelerated 4D Phase Contrast Velocimetry of Intracranial Aneurysms

09:18 Discussion for Morphology of intracranial aneurysms



09:54 – 11:44 Session 5 Peripheral MRA

Session Chairs : Vivian Lee, Jeffrey Maki

Non-Contrast Peripheral MRA

09:54 Sandra Huff 5.1 Continuously Moving Table Venography and Arteriography

10:06 Ioannis Koktzoglou 5.2 FERAL MR Angiography for Rapid, Quantitative Flow Imaging of the Peripheral Arteries

10:18 Iliyana Atanasova 5.3 3 Station Non-contrast-enhanced Angiography of the Aortoiliac and Lower Extremity Arteries at 1.5T

10:30 Mitch Cooper for Thanh Nguyen 5.4 Three Dimensional Non-Contrast MRA of the Lower Extremities with Stepping Thin Slab Acquisition: A Feasibility Study in Healthy Subjects

Bolus chase MRA

10:42 Jim Meaney 5.5 Effective 5-station whole body contrast-enhanced MRA at 3T with reduced contrast dose, tourniquet thigh compression, and combined neurovascular coil and body coil.

10:52 Giles Roditi 5.6 MultiMRA - Initial Experience of Single Dose Gadobenate dimeglumine for Compre-hensive MR Angiography of the Lower Limbs with Dynamic Calf, 3 Station Bolus Chase & High-Resolution Extended Phase Imaging

11:02 Jeffrey H. Maki 5.7 A Timing Algorithm Strategy for pMRA

11:12 Discussion of bolus chase MRA

Time-resolved MRA of the calf 11:20 Ioannis Koktzoglou

5.8 Highly Accelerated Contrast-Enhanced MRA: Benefit of Complex Subtraction

11:32 Phillip M. Young 5.9 Comparison of CAPR MRA with CT Angiography for Evaluation of Below the Knee Runoff:Preliminary Results

11:44 – 13:00 Lunch


13:00 – 13:36 Session 6 Interventional MR

Session Chairs : Ethan Brodsky, Orhan Unal 13:00 Emre Özda

6.1 XIP Software Suite for XFM (X-Ray Fused with MRI)

13:12 Orhan Unal 6.2 Multi-baseline PRF-based Thermometry for MR-guided Interventions using an Extensible Real-Time Platform

13:24 Ethan Brodsky for Walter F. Block 6.3 Fat-Suppressed Steady State Imaging for Non-Contrast Enhanced MR Angiography in the Thorax & Abdomen

13:36 – 15:24 Session 7 New MRA techniques

Session Chairs : Richard Frayne, Ethan Brodsky

13:36 Dennis Parker 7.1 Unlocked Motion in Turbo Spin Echo of the Cervical Carotid Artery

13:48 Mitsuharu Miyoshi

7.2 Phantom study of Black Blood CUBE with Flow-Sat-Prep

14:00 Alex J Barker 7.3 Acceleration-sensitive MRI: Analysis of Complex Vascular Flow Patterns

14:12 Nahee Lee 7.4 Multivariate Measurement of Trans-stenotic Pressure Gradient

14:24 Yi Wang 7.5 Quantitative Susceptibility Mapping of Intracerebral Hemorrhage

14:36 Ethan Brodsky 7.6 Developing Guidelines for Successfully Interleaving Active Tracking of Catheters with Steady-state Imaging Sequences

14:48 Liesbeth Geerts 7.7 An automated approach to vessel lumen analysis – Vessel Explorer

15:00 Chang-Ki Kang

7.8 Potentials of ultra high field strength 7T MRA: Comparison with other imaging modalities

15:12 Hwayoung Kate Lee

7.9 Web Based MRA Protocols



15:44 – 17:10 Session 8 Compressed sensing and HYPR

Session Chairs : Stephen Riederer, Charles Mistretta 15:44 MA Bernstein

8.1 Compressive Sensing Reconstruction Improves Low-contrast Detectabililty

15:54 Jerome Yerly 8.2 Accelerating 3D TOF with Compressed Sensing

16:04 Julia Velikina 8.3 A New Compressed Sensing and Magnitude Constraint Based Approach to Acceleration of Phase Contrast Velocimetry

16:14 Lauren Keith 8.4 Parallel Imaging with Hybrid 3D Radial Acquisition for HYPR Reconstruction

16:24 Discussion for compressed sensing and HYPR

16:32 Kang Wang 8.5 3D Time-Resolved MRA of Lower Extremities using Interleaved Variable Density Sampling, Parallel Imaging and Cartesian HYPR Reconstruction

16:42 Casey P. Johnson

8.6 Time-Resolved Calf-Foot 3D Bolus-Chase MRA

16:52 Yijing Wu

8.7 HYPR CE: High resolution 4D contrast enhanced MRA using single dose, dual injection and constrained reconstruction

17:02

Discussion for compressed sensing and HYPR


Friday, Oct 8th

08:00 – 09:36 Session 9 Coronary MRA and Cardiac

Session Chairs : Yi Wang, Stefan Rhuem 8:00 Jing Liu

9.1 Self-Gated Free Breathing 3D Coronary Cine Imaging With Simultaneous Water and Fat Visualization

8:12 Qi Yang 9.2 Integrating High Spatial-Resolution, 3D Whole-Heart Viability Imaging and Coronary MRA at 3 Tesla

8:24 Chang-Beom Ahn 9.3 Removal of Eddy-Current Effects in Multiphase Cardiac Flow Imaging

8:36 Daniela Föll 9.4 Left ventricular MR velocity mapping: radial and long-axis dyssynchrony

8:48 John N. Oshinski 9.5 Coronary Vein Motion in Patients Undergoing Cardiac Resynchronization Therapy: Implications for MR Coronary Venography

9:00 Teruhito Mochizuki 9.6 Assessment of Myocardial Perfusion --- Comparison of CT, MR and NM ---

9:12 Grace Choi 9.7 ECG-Gating for MRA

9:24 Yutaka Natsuaki 9.8 A Novel Approach to ECG-Gated High Resolution Contrast-Enhanced MR Angiography in a Single Breath Hold



10:06 – 11:56 Session 10 Abdominal MRA

Session Chairs : Winfried Wilinek, Giles Roditi

Contrast-enhanced Renal MRA

10:06 Honglei Zhang 10.1 Comparison of Renal MRA/CTA and Angiography Data in CORAL Study

10:16 Parmede Vakil 10.2 Combined Renal MRA and Perfusion with a Single Dose of Contrast

10:26 Discussion of contrast Renal MRA

Non-contrast MRA

10:32 Mitsue Miyazaki 10.3 Non-Contrast MRA at 3T

10:44 Manojkumar Saranathan 10.4 Breath-held non-contrast enhanced MR angiography with a novel group- encoded k-space segmentation method

10:56 Takayuki Masui 10.5 Evaluation of the renal arteries using two types of Non-contrast MRA: FIESTA with flow preparation pulse and FIESTA with Inhance Inflow IR technique

11:08 Pauline W Worters 10.6 Improved signal in inflow-sensitive bSSFP MRA using variable flip angles

Time-resolved abdominal MRA 11:20 Petrice Mostardi

10.7 High Temporal and Spatial Resolution Abdominal CE-MRA

11:32 Pascal Spincemaille 10.8 Respiratory Gated Contrast-Enhanced MRA of the Liver

11:44 Kevin M. Johnson 10.9 Rapid Angiography and Perfusion with Multi-Echo 3D Radials and an Echo Weighted Constrained Reconstruction

11:56 – 13:26 Lunch


13:26 – 14:50 Session 11 Intra-cerebral MRA

Session Chairs : Dennis Parker, Thorsten Bley 13:26 Chan-A Park

11.1 3D Visualization of the lenticulostriate artery and the correlated infarct

13:38 Parmede Vakil 11.2 High Resolution 2D Radial FLASH MR DSA for Intracranial Vascular Disease

13:50 Rotem S Lanzman 11.3 Nonenhanced ECG-gated time-resolved 4D Steady-State Free Precession MR Angiography (4D SSFP MRA) in assessment of intracranial collateral flow: comparison with digital subtraction angiography (DSA).

14:02 Dariusch Hadizadeh 11.4 High-spatial resolution time-resolved 4D MR angiography of cerebral arteriovenous malformations: experience in 50 patients using different MRA protocols and different contrast agents

14:14 Chang-Woo Ryu 11.5 High Resolution Vessel Wall MRI of the Chronic Unilateral Middle Cerebral Artery Occlusion

14:26 Keiji Igase 11.6 Effectiveness of Fat-Suppression MRAngiography Comparing with Standard 3D-TOF MRA in Revealing Cerebrovascular Diseases.

14:38 Hitoshi Miki 11.7 3-Tesla VR Images of Brain Tumor: Pre-surgical planning


15:10 – 17:00 Session 12 Neck MRA, Vessel Wall Imaging

Session Chair : Kevin DeMarco

Neck MRA

15:10 Kevin DeMarco Current status of Neck MRA

15:22 Bum-soo Kim 12.1 Supra-aortic Vascular Pathologies on Low Dose Time-Resolved CEMRA


Vessel Wall imaging

15:34 Jason Mendes 12.2 CINE Turbo Spin Echo Imaging

15:46 Michele Anzidei 12.3 High resolution steady state MR angiography: optimization of the technique and clinical results in the carotids

15:58 Hideki Ota 12.4 Sex Differences of High-Risk Carotid Atherosclerotic Plaque Along with Different Levels of Stenosis – in vivo 3.0T MRI study

16:10 Rui Li 12.5 Quantitative Measurement of MR Constants in Carotid Plaque at 3T

16:22 Jie Zheng 12.6 Atherosclerotic Plaque Imaging with SWI Approach

16:34 Giacomo DE Papini 12.7 Evaluation of Inflammatory Status of Atherosclerotic Carotid Plaque before Thromboendarterectomy using Delayed Contrast-enhanced Subtracted images after Magnetic Resonance Angiography

16:46 ZR Lu for Xueming Wu 12.8 A Targeted Contrast Agent Specific to Fibronectin for MR Molecular Imaging of Atherosclerotic Plaques

16:58 MRA Club 2011 Meeting Announcement

Closing Remark


Electronic Posters

P1 Tae-Sub Chung The Relationship of Asymmetric dilatation of Virchow-Robin space and Ipsilateral Internal Carotid Artery stenosis on MRA

P2 Hua Guo Protocol Optimization for Non-Contrast Enhanced MRA of the Abdominal Aorta at 1.5 and 3 T

P3 Thomas A. Hope The Effect of Omniscan on Hypoxia Inducible Factor-1α (HIF-1α) in Macrophages

P4 Jin Hur Use of contrast-enhancement and high-resolution 3D black-blood MR Imaging to identify inflammation in rabbit atherosclerotic plaques

P5 Seong-Eun Kim Arterial Spin Labeling Perfusion Measurement using 3D single shot Stimulated Echo Planer Imaging (3D ss-STEPI) and FAIR at 3 Tesla

P6 Tiffany Newman Magnetic Resonance Lymphangiography for the preoperative assessment of upper extremity lymphedema

P7 Seung-Taek Oh Effect of stellate ganglion block on cerebrovascular system: MRA study

P8 Weckbach, Sabine Dynamic 3D MR Angiography for the Assessment of Rheumatoid Disease of the Hand

P9 Dalmo Yang Time-Resolved MR Angiography for Detecting and Grading Ovarian Venous Reflux: Comparison with Conventional Venography

P10 Sun Mi Kim Diagnosis of Vertebral Artery Ostial Stenosis on Contrast-Enhanced MR Angiography: Usefulness of a Thin-Slab MIP Technique

P11 Reed Busse Separating Coherent Aliasing from Incoherent Artifacts in a Highly Undersampled Acquisition - A Point Object Experiment.

P12 Harald Quick Towards Real-Time MR-Guided Transarterial Aortic Valve Implantation (TAVI)

P13 Nicoletta Anzalone Follow-up of y Knife treated arteriovenous malformations: usefulness of 4D MR Angiography and 3D GE Steady State acquisition after gadobutrol at 3T

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1.1 Decrease in acute adverse reactions to gadobenate dimeglumine

Emanuel Kanal, MD University of Pittsburgh Medical Center, Pittsburgh, PA, USA

Purpose: Since publication of our initial safety experience with gadobenate dimeglumine (MultiHance, Bracco Diagnostics Inc.) in 2008 (1), we have continued to prospectively collect adverse event (AE) data associated with the use of this agent at our institutions. Herein we present the updated data on the safety of gadobenate dimeglumine in routine clinical practice. Methods: Under approval of the Quality Assurance (QA) Committee of our institution, we prospectively assessed all consecutive clinical patients who received gadobenate dimeglumine at several of our Health Center institutions for the duration of the project. Each center participated in this QA project for varying lengths of time/numbers of patients, ranging from as few as 354 consecutive patients to as many as 52,700. Adverse reaction rates were determined for each institution and collectively for the group as a whole. For the initial 23,553 patients included in this QA project, all adverse reactions were analyzed by type, class (allergic versus non-allergic), severity, whether or not they required treatment and if so, what treatment was administered, and ultimate patient disposition/status. Results: A total of 89,991 consecutive patient injections have thus far been included in this ongoing QA project. AEs of all types and severities from all institutions of origin totaled 404, or 0.5%, a highly significant reduction from our initial reported rate of 0.76 in 2008 (P<0.0001, Pearson’s chi-square). A consistently decreasing reaction rate over time has been noted for the institutions which have continued to participate in this project over several years. For example, at our largest institution, an AE rate of 0.5% (13,552 injections, 63 adverse reactions) in 2008 has now fallen to 0.3% (52,700 injections, 122 reactions), a highly significant reduction (P<0.0001). Serious AEs (as defined by the FDA, including life threatening reactions and/or those that required hospitalization) occurred at an overall rate of 0.034%. About 20% of AEs were allergic in nature. No deaths were experienced. A single anaphylactoid reaction occurred which was successfully treated with epinephrine, diphenhydramine, and methylprednisolone. Conclusions: The rate of both non-serious and serious AEs after gadobenate dimeglumine is low and consistent with published data on AE rates with other gadolinium-based contrast agents, including previous experience with other agents at our institution (2). References: 1. Bleicher AG, Kanal E. Assessment of adverse reaction rates to a newly approved MRI

contrast agent: review of 23,353 administrations of gadobenate dimeglumine. AJR 2008; 191:W307-W311

2. Hieronim DE, Kanal E, Swanson DP. Dosage of gadoteridol and adverse reactions relative to gadopentetate. Am J Health-Syst Pharm 1995; 52:2556-2559


1.2 Comparison of Blood-Pool and Extracellular Contrast Agents on MRA of Abdominal Perforator Flap Arteries

Zhitong Zou, Michelle Cerilles, David T Greenspun, Joshua L Levine, Julia Vasile, Constance Chen, Christine Ahn and Martin R Prince. Departments of Radiology and

Plastic Surgery, Weill Cornell Medical College, New York, USA Purpose: During routine imaging of deep inferior epigastric perforator vessels in preparation for autologous donation of abdominal fat for breast reconstruction, plastic surgeons noted that image quality was superior using blood pool contrast agents compared to extracellular agents. Here we compare blood pool contrast agent (gadofosveset trisodium, 10ml) and an extracellular contrast agent (gadobenate dimeglumine, 20ml) on MRA of abdominal perforator flap artery. Methods: 44 consecutive patients undergoing breast mastectomy and reconstruction had pre-operative perforator flap artery MRA (22 with gadofosveset trisodium, 22 with gadobenate dimeglumine). Bilateral common femoral artery (CFA), Inferior Vena Cava (IVC) and rectus perforator SNR and CNR were measured as well as rectus abdominis muscles and anterior subcutaneous fat on coronal LAVA images. In addition perforator sharpness was measured and the number of perforators visualized were compared with students’ t test for unpaired data. Results/Discussion: The mean number of perforator arteries visualized with gadofosveset trisodium was 5.8 on right and 8.9 on left compared to 3.7 on right and 5.6 on left for gadobenate dimeglumine (p=0.001). SNR was comparable for the two contrast agents suggesting the difference was not dose related. Gadofosvest had less muscle enhancement so the artery to muscle contrast was greater for gadofosveset 0.7 compared to gadobenate 0.6 (p<0.01). Perforator sharpness was also greater for gadofosveset. Surgeons noted that the detailed information about the vessels including course through the rectus abdominis and branching patterns were superior for blood pool studies. All perforators visualized on MRA were found at surgery (0% false-positive) and the grafts were successful. Conclusion: Artery/muscle contrast is higher with gadofosveset trisodium compared to gadobenate dimeglumine at comparable arterial SNR suggesting that the blood pool effect enhances image contrast. The improved sharpness of perforators may relate to less enhancement of the vessel wall smooth muscle with the blood pool agent.

Figure 1. (left) 42-year-old female had abdominal perforator flap artery MRA using 10ml gadofosveset trisodium. (right) Another female of the same age had abdominal perforator flap artery MRA using 20ml gadobenate dimeglumine.(Red arrows indicate perforators). Perforators vascular course in the subcutaneous fat and rectus muscle is superior with the blood pool agent (left) compared to extracellular contrast, gadobenate dimeglumine. References: 1. Perforator flap magnetic resonance angiography for reconstructive breast surgery: a review of 25 deep inferior epigastric and gluteal perforator artery flap patients. JMRI, 2010, 5;31(5):1176-1184. 2. Anatomic imaging of abdominal perforator flaps without ionizing radiation: seeing is believing with magnetic resonance imaging angiograp. J Reconstr Microsurg. 2010, 1;26(1):37-44. 3. Highly accelerated first-pass contrast-enhanced magnetic resonance angiography of the peripheral vasculature: comparison of gadofosveset trisodium with gadopentetate dimeglumine contrast agents. JMRI. 2009, 11;30(5):1085-1092.


1.3 DCE MRI with Gadofosveset in Peripheral Arterial Disease: Assessment of the Hyperemic Microvascular blood

volume Bas Versluis, MD1,3; Patty J. Nelemans, MD PhD2; Joachim E. Wildberger MD, PhD1,3,

Walter H. Backes, PhD1,3; Tim Leiner MD, PhD 1,3,4 Maastricht University Medical Center, Departments of Radiology1 and Epidemiology2 and Cardiovascular Research Institute Maastricht (CARIM)3, Department of Radiology, Utrecht

University Medical Center4

Purpose The objective of this study was to determine suitable functional parameters reflecting the hyperemic microvascular blood volume of the calf musculature and to investigate their ability to discriminate between patients with peripheral arterial disease (PAD) and healthy control subjects, using a blood pool contrast agent (gadofosveset trisodium) in dynamic contrast-enhanced (DCE) MRI. Methods Ten patients with proven PAD (intermittent claudication) and 10 healthy volunteers were included and underwent DCE MRI of the calf musculature. The MR protocol consisted of DCE perfusion imaging to determine maximum contrast concentration of muscle tissue (Cmax, unit: µM) and the hyperemic fractional microvascular blood volume (Vp, unit: %) of the anterior tibial, gastrocnemius and soleus muscles. DCE data were acquired under reactive hyperemia conditions. Results A trend of lower values for Cmax was found in PAD patients for all muscle groups (range differences 0.1 - 2.8 µM), including a significant lower Cmax for the anterior tibial muscle (p = 0.04). Vp was significantly lower for all muscle groups in PAD patients compared to healthy volunteers (range differences 1.5 - 4.8 %, p < 0.01). . These data suggest that symtpomatic PAD is accompanied by microvascular changes in addition to macovascular disease. Conclusions DCE MRI using a blood pool contrast agent is able to determine the fractional hyperemic microvascular blood volume of the calf musculature and to discriminate between PAD patients and healthy control subjects. Blood pool agents are therefore a valuable addition to DCE MRI in PAD and can be applied in clinical practice to accurately determine the microvascular blood volume.


1.4 Safety of 1.0M macrocyclic gadobutrol in mr angiography in pediatric patients – A German multicenter analysis

G. Hahn1, W. Hirsch2, H.J. Mentzel3 1Institut und Poliklinik für Radiologische Diagnostik Bereich Kinderradiologie am

Universitätsklinikum Carl-Gustav-Carus der Technischen Universität Dresden, Dresden, Germany

2 Selbstständige Abteilung pädiatrische Radiologie der Universität Leipzig, Leipzig, Germany

3Pädiatrische Radiologie, Institut für Diagnostische und Interventionelle Radiologie Universitätsklinikum,Jena, Germany

Purpose: To evaluate the safety and applicability of 1.0 M gadobutrol in infants, children and adolescents referred for MR angiography in clinical routine. Methods: Paediatric patients between 2 and 17 years scheduled for CE- MRA received a single intravenous injection of gadobutrol (0.1 mmol/kg body weight) followed by a saline flush. Examinations were performed on 1.5 T (Siemens Avanto or Sonata, Philipps Intera) and 3T (Siemens Trio) systems. 3D angiographic examinations were time resolved and spatial resolution was adapted. Smallest field of view was selected and adapted to body size. Sedation was applied if necessary. Safety was evaluated by a questionnaire immediately after the examination and by phone one day after contrast media application. Results and Discussion: Gadobutrol is already widely used for CE-MRA in adults. A recent publication has shown superior vessel-to-tissue contrast compared to gadopentetate in abdominal 3D angiography1. The safety of 1.0 M gadobutrol in pediatric populations has been demonstrated in a meta analysis of six prospectively planned surveillance studies including 183 patients below the age of 182. In a recent clinical pharmacokinetic study the safety of 1.0 M gadobutrol was shown for 138 patients. No dose adjustment from the standard dose of 0.1 mmol/kg BW gadobutrol was necessary in paediatric patients aged 2-17 years. Incidence and profile of adverse drug reactions were similar to adults3. In our analysis of 30 clinical routine cases we investigated the safety and applicability of 1.0 M gadobutrol for CE-MRA in the pediatric population. Typical cases included the detection of stenosis of extracranial arteries, detection of vascular malformations as well as the evaluation of vessel anatomy in children suffering from tumors for presurgical planning. Conclusion:. 1.0 M gadobutrol can be safely administered in pediatric patients for CE-MRA. Safety and tolerability of gadobutrol were confirmed in this pediatric population in a real life setting. The standard dose of 0.1 mmol/kg body weight was sufficient to generate high quality images. References:

1) Hadizadeh et al, AJR 2010; 194:821-829 2) Forsting M, and Palkowitsch P, Eur J Radiol 2009; doi 10.1016 3) Hahn et al, Invest Radiol 2009; 44: 776-783

Key words: gadobutrol, pediatric population, safety


1.5 Low Dose (0.1 mmol/kg) Gadodiamide-Enhanced Magnetic Resonance Angiography (MRA) for Detection of Renal Artery or

Aortoiliac Occlusive Disease: Results of Two Multicenter, Prospective International Trials

Rubin Sheng, MD, MPH Department of Clinical Development, GE Healthcare, Medical Diagnostics, Princeton, New Jersey, USA

PURPOSE: To evaluate the diagnostic efficacy of contrast-enhanced Magnetic Resonance Angiography (CE MRA) with Gadodiamide administration at a dose of 0.1 mmol/kg for detection of renal arterial or aortoiliac occlusive disease when compared to the reference standard, intra-arterial digital subtraction angiography (IA DSA) and non-contrast MRA. METHODS: Two multicentre, prospective, international trials of Gadodiamide-enhanced MRA were conducted worldwide to establish the diagnostic utility of CE MRA in the renal and aorto-iliac arterial stenoses. Patients with suspected or proven renal artery stenosis or aortoiliac arterial occlusive disease and referred for elective IA-DSA, were enrolled. Patients with hypersensitivity to gadolinium agent or with severe kidney dysfunction were excluded. The studies received institutional review board or ethic committee’s approval at each center prior to commencement of patient enrollment. A non-contrast MRA was performed initially, followed by CE MRA after Gadodiamide administration at a dose of 0.1 mmol/kg. Elective IA-DSA was performed within one month of the MRA procedure. MRA images were interpreted by 3 independent blinded readers for presence of hemodynamically relevant stenosis (≥50% stenosis or occlusion) in renal or aortoiliac arteries. The final diagnosis of MRA images was based on majority decision by at least 2 blinded readers. IA-DSA images were independently interpreted by 2 blinded readers then achieved consensus to serve as the reference standard. Sensitivity, specificity and accuracy of MRA images were analyzed for both intend-to-diagnose (ITD) population which comprised patients with interpretable IA-DSA and available MRA images (irrespective interpretability) and per-protocol population in which both IA DSA and MRA images were deemed as interpretable for a subject. McNemar's Test (exact) was used to test difference of two MRAs at 1-sided p-value of <0.025. RESULTS AND DISCUSSION: A total of 730 patients were included in the ITD analysis. Of these, 63% were male and 37% were female. The mean age was 63.4 years. The efficacy results are presented as follow:

The two clinical trials included more than 700 patients. The diagnostic performance of Gadodiamide administration at low dose of 0.1 mmol/kg for CE MRA in patients with suspected or known renal artery or aortoiliac occlusive disease was evaluated. The sensitivity, specificity and accuracy of Gadodiamide MRA and non-contrast MRA were compared to the reference standard, IA-DSA. Gadodiamide MRA demonstrated favorable results in comparison to reference standard, IA-DSA and to those reported results by single center study in consideration of multicenter study environment with diversified investigator experiences on MRA across centers and rigorous blinded read process applied in the efficacy evaluation. More importantly, the results of Gadodiamide MRA are statistically significantly superior to that of non-contrast MRA. CONCLUSION: Gadodiamide administration at the labeled dose of 0.1mmol/kg for CE MRA is an effective and accurate technique for detecting hemodynamically relevant arterial stenoses in the renal and aorto-iliac vascular territories. Its diagnostic efficacy is superior to and more consistent than that of non-contrast MRA.

Sensitivity, specificity and accuracy of Gadodiamide MRA and non-contrast MRA for detection of hemodynamically relevant stenosis (≥50% or occlusion)

Parameter Procedures Number of Patients

Diagnosis by IA-DSA

Diagnosis by MRA MRA Comparison

N n n’ % p-value ITD

Analysis Sensitivity Gadodiamide MRA 730 433 357 82.4 <0.0001

Non-contrast MRA 730 433 257 59.4 Specificity Gadodiamide MRA 730 297 235 79.1 <0.0001

Non-contrast MRA 730 297 168 56.6 Accuracy Gadodiamide MRA 730 730 592 81.1 <0.0001

Non-contrast MRA 730 730 425 58.2 Per-

Protocol Analysis

Sensitivity Gadodiamide MRA 695 418 357 85.4 <0.0001 Non-contrast MRA 611 367 257 70.0

Specificity Gadodiamide MRA 695 277 235 84.8 <0.0001 Non-contrast MRA 611 244 168 68.9

Accuracy Gadodiamide MRA 695 695 592 85.2 <0.0001 Non-contrast MRA 611 611 425 69.6


1.6 High resolution vessel wall imaging in giant cell arteritis: 7 years experience

TA Bley1, J. Geiger2, M. Markl2, O. Wieben3, M Uhl2 1 Department of Radiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany,

2 Department of Radiology and Medical Physics, University Hospital Freiburg, Freiburg, Germany, 3 Departments of Medical Physics and Radiology, University of Wisconsin-Madison, Madison, WI, USA Purpose: To evaluate the diagnostic potential of high resolution vessel wall MRI for assessment of mural inflammation in the superficial temporal arteries in giant cell arteritis (GCA) combined with MRA for evaluating the extend of the disease. Methods: In the past seven years we have scanned 219 patients with GCA or suspected of GCA, mostly utilizing a 3T MRI scanner (Magnetom Trio, Siemens Medical Solutions, Erlangen, Germany) equipped with a dedicated eight element phased-array head-coil: Post-contrast, fat saturated multislice T1-weighted spin echo images were acquired in a transversal plane with a sub-millimeter, ultra-high spatial in-plane resolution of 195 µm 260 µm (TR/TE = 500/22 ms, FoV = 200 200 mm2, 　　acquisition matrix size = 1024 768 voxels, bandwidth 　 (76 Hz/pixel), partial Fourier encoding (partial Fourier factor = 6/8), number of excitations = 1). Eleven slices with a slice thickness of 3 mm and slice distance of 3 mm covered a volume that stretched over 63 mm in an acquisition time of 4:52 min. Image acquisition was initiated approximately 1 minute after venous injection of 0.1 mmol/kg of a Gd-BOPTA (Multihance , BRACCO, NJ). Temporal artery biopsy was used as diagnostic gold standard 　when available. The clinical diagnosis in accordance with the American College of Rheumatology criteria was used as a clincial reference standard when no biopsy was obtained. Follow-up examinations under varying duration of steroid therapy were performed in a subset of patients to evaluate the influence of treatment on the mural inflammatory changes. Diagnositc performance of high resolution MRI was compared with color coded duplex sonography (CCDS) in patietns that had undergone both imaging studies. The intracranial and intradural involvement was assessed in histologically proven GCA-patients. Results: Contrast-enhanced, high-resolution MR imaging allowed noninvasive assessment of mural inflammation and cranial involvement pattern in giant cell arteritis with a sensitivity of 80.6% and a specificity of 97.0%1,2. The high specificity may be explained by a potential referral bias in this particular patient cohort. Measures of mural thickening and contrast enhancement can be obtained in these small vessels and provide valuable vasculitic MR imaging findings at 1.5 T and 3T 1,3. The mean wall thickness increased significantly from 0.39 mm ( 0.18 mm) to 0.74 mm ( 0.32mm; P<0.001) in 　　patients with giant cell arteritis2. Mural contrast enhancement in high-resolution MRI was pronounced in active disease and decreased under corticosteroid treatment within 10 days and vanished entirely at several months follow-up, correlating well with laboratory remission4. The intracranial/extradural medial menigeal arteries revealed the same mural inflammatory changes seen in the superficial temporal arteries in 32% of cases in a subgroup of histologically validated GCA patients while the thin walled intradural arteries of the circle of Willis did not present any inflammatory changes5. A retropsective analysis that compared resulkts of MRI with CCDS and that used temporal artery biopsy as diagnostic gold standard revealed a sensitivity of high-resolution MRI and CCDS of 83% and 79%, respectively, and a specificity of 71% and 59%, with a PPV of 80% and 73%, and NPV of 75% and 67%, respectively. The differences between high-resolution MRI and CCDS were not large enough to reach the level of statistical significance in this patient cohort6. Conclusion: High resolution vessel wall imaging depicts mural inflammatory changes in active GCA. In combination with MRA the intra- and extracranial extend of the disease can be assessed. Effects of steroid treatment can be monitored and relapsing disease that is very difficult to diagnose clincially may be visualized with MRI. High resolution MRI has the potential to replace temporal artery biopsy when the diagnostic accuracy of this technique is validated in larger patient trials. References: 1 Bley TA et al., Arthritis&Rheumatism 2005;52(8):2470–2477 ,2 Bley TA et al., Am J Neuroradiol 2007;28:1722–27, 3 Bley TA et al., AJR 2005;184:283–287, 4 Bley TA et al., Rheumatology 2008;47:65–67, 5 Bley TA et al., Annals Rheumatic Disease 2009;68:1369–1370 6 Bley TA et al., Arthritis&Rheumatism 2008;58(2):2574 –2578


2.1 Signal quality of single dose gadobenate dimeglumine pulmonary MRA examinations exceeds quality of MRA

performed with double dose standard gadolinium-based agent

Pamela K. Woodard, MD1 , Thomas L. Chenevert, PhD2, H. Dirk Sostman, MD3, , Kathleen A. Jablonski, PhD4, Paul D. Stein, MD5, Lawrence R. Goodman, MD6, Frank J.

Londy, PhD2, Vamsidhar Narra, MD1, Charles A. Hales, MD7, Russell D. Hull, MBBS, MSc8, Victor F. Tapson, MD9, John G. Weg, MD2

1Department of Radiology, Washington University, St. Louis, Missouri, 2Department of Radiology, University of Michigan, Ann Arbor, Michigan, 3Office of the Dean and

Department of Radiology, Weill Cornell Medical College and Methodist Hospital, Houston, Texas

4The Biostatistics Center, George Washington University, Rockville, Maryland, 5Department of Internal Medicine, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, 6Department of Radiology, Medical College of

Wisconsin, Milwaukee, Wisconsin, 7Department of Medicine, Massachusetts General Hospital, and Harvard Medical School, Boston, Massachusetts, 8Department of Medicine,

University of Calgary, Calgary, Alberta, Canada, 9Department of Medicine, Duke University, Durham, North Carolina

Purpose: During a recent multi-center trial assessing gadolinium (Gd)-enhanced magnetic resonance angiography (MRA) for diagnosis of acute pulmonary embolism (PE), the Food and Drug Administration announced a risk of nephrogenic sclerosing fibrosis (NSF) in patients with renal insufficiency who had received intravenous Gd-based MR contrast agents. To reduce risk, the trial protocol was changed from an intravenous administration of 0.2 mmol/Kg of a conventional Gd-based MR contrast agent to 0.1 mmol/Kg of gadobenate dimeglumine. The study described herein compares the signal quality of pulmonary MRA performed with double dose conventional agent to single dose gadobenate dimeglumine. Methods: This study is a retrospective analysis of data from a prospective, multicenter study in men and women ≥ 18 years with documented presence or absence of PE. The study was approved by the Institutional Review Board at all participating centers, and all patients provided written indication of informed consent. We performed both objective and subjective analysis of pulmonary artery image quality. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in the main pulmonary artery were assessed in single and double dose protocols and compared. SNR and CNR of the main PA were correlated with subjective quality assessment of main/lobar, segmental and subsegmental pulmonary arteries. Results: Both SNR (P = 0.01) and CNR (P=0.008) were higher on examinations using gadobenate dimeglumine than with gadopentetate dimeglumine. Subjective quality of vascular signal intensity at each vessel order was significantly better for gadobenate dimeglumine (P<0.0001), and correlated well with SNR and CNR at each order (<0.001). Conclusion: Because of agent high relaxivity, a single dose of gadobenate dimeglumine provides better pulmonary MRA signal quality than double dose of a conventional Gd-based MR contrast agent. ClinicalTrials.gov Identifier: NCT00241826 SUPPORT: This study was supported by Grants HL081593, HL177150, HL077149, HL077151, HL077154, HL081594, HL077358, HL077155, and HL077153 from the U.S. Department of Health and Human Services, Public Health Services, National Heart, Lung, and Blood Institute, Bethesda, Maryland


2.2 Features of COPD on time-resolved Pulmonary MRA

Kana Fujikura, Wei Zhang, Corey Ventetuolo, Joao Lima, David Bluemke, Graham Barr, Martin R. Prince

Department of Radiology, Columbia University, NY, USA Purpose: As part of an NIH study of Chronic Obstructive Pulmonary Disease (COPD), patients of varying disease severity are undergoing Pulmonary MRI including time-resolved pulmonary MRA. Here we investigate the MRA features which are associated with COPD severity. Methods: Time-resolved pulmonary MRA using TRICKS at 1.5 second temporal resolution, matrix = 256 x 128 x 20 with 2-fold zero filling in the slice direction, TR/TE/flip = 2.4/.8/20 at 1.5Tesla using a cardiac phased array coil on a GE EXCITE scanner. Participants were recruited from an ongoing prospective cohort study of current and former smokers, age 58-79 years, and free of clinical cardiovascular disease. COPD was defined on post-bronchodilator spirometry by GOLD criteria. Images were evaluated for pulmonary arterial pruning, tortuosity, rapid tapering, and parenchymal perfusion. Results: Participants with COPD had global lung fields with blotchy-looking perfusion, reduced angle of pulmonary arteries, larger descending aorta compared to normal volunteers (p<0.05). Also COPD patients tend to show rapid tapering and ectasia of the thoracic aorta compared to normal volunteers. Conclusion: Time-resolved Pulmonary MRA identifies distinct features of COPD. This may help evaluate patients with pulmonary disease and may allow diagnosis and grading of pulmonary disease when time-resolved MRA of the thorax is performed as part of investigating another condition.

COPD severity N

perfusion PA diameter Ao diameter patchy (%) ratio to branch arch (mm) descending (mm)

Normal 31 67.9 0.467±0.211 24.8±3.1 19.0±2.8 Mild 14 92.9 0.536±0.245 25.7±3.3 20.4±3.1 Moderate 15 100.0 0.345±0.101 28.0±3.7 22.4±3.8 p-value 0.0062 0.0606 0.0672 0.0108

Table 1. Time-resolved MRA features.

Figure 1. Selected images from a time series of TRICKS in a patient with mild COPD.


2.3 Dynamic Pulmonary Perfusion Imaging using Interleaved Variable Density Sampling, Parallel Imaging and Cartesian

HYPR Reconstruction 1aK. Wang, 1a,bF.R. Korosec, 1aN.S. Artz, 1bM.L. Schiebler, 1bC.J. Francois, 1a,b,cS.B. Reeder,

1bT.M. Grist, 2R.F. Busse, 2J.H. Holmes, 1a,b,cS.B. Fain, 1bS.K. Nagle 1aMedical Physics, 1bRadiology, 1cBiomedical Engineering, University of Wisconsin,

Madison, WI 2Applied Science Lab, GE Healthcare, Madison, WI

Purpose: To obtain high spatial and temporal resolution 3D dynamic pulmonary MR perfusion images using Cartesian interleaved variable density (IVD) sampling [1], parallel imaging (PI) [2] and Cartesian HYPR [3,4] reconstruction. Methods: During data acquisition, the k-space for each time frame is undersampled in the ky-kz plane by a factor of 4 using PI and another factor of 2.5 using IVD (Fig. 1). In the reconstruction, a data driven parallel imaging method [2] was integrated with a Cartesian multiplicative constrained reconstruction (HYPR) [4] to unfold the aliased image and suppress incoherent artifacts caused by IVD. Imaging parameters include: TR/TE = 1.8/0.5ms, 75% fractional echo, and 4.0mm isotropic resolution with FOV of 40(S/I) × 40(L/R) × 22(A/P) cm3. Sixteen frames were resolved at 1.0 sec/frame with a 19-second breath-hold (including 3 sec of mask). 10mL of Gd-BOPTA was injected at 3mL/s for a healthy volunteer exam. Results: Fig. 2 shows dynamic perfusion images for selected slices along each axis, showing isotropic resolution and excellent parenchymal signal. Fig. 3 illustrates representative coronal slices from a single timepoint during the parenchymal phase, demonstrating the excellent image quality across the entire volume, with very little artifact due to cardiac motion.

Conclusion: It is feasible to obtain very high isotropic spatial resolution 3D dynamic pulmonary perfusion images of the whole chest with very high temporal resolution using IVD, PI and Cartesian HYPR reconstruction. References: [1] Busse et al., ISMRM 2009, p4534. [2] Brau et al. MRM 59:382 (2008) [3] Mistretta et al. MRM 55:30 (2006). [4] Wang et al. ISMRM 2010, p352

Figure 1. Sampling pattern for a typical time frame.

Figure 2. Coronal, axial and sagittal reconstructions from dynamic, whole-chest pulmonary perfusion MRI with 4.0mm isotropic resolution and 1.0s temporal resolution. Figure 3. 4.0 mm coronal reconstructions showing uniform parenchymal enhancement (t=12s).


2.4 Preoperative mapping of autogenous saphenous veins as an imaging adjunct to peripheral MR angiography in patients

with PAOD and femorodistal bypass grafting: Prospective comparison with ultrasound and intraoperative findings Jah-Kabba AM1, Kukuk GM1, Hadizadeh DR1, Koscielny A², Verrel F², Schild HH1,

Willinek WA1 1University of Bonn, Dept. of Radiology

2University of Bonn, Dept. of Vascular Surgery Purpose: To evaluate the diagnostic value of steady state images as an adjunct to peripheral MR angiography (MRA) with a blood pool contrast agent (BPCA) in patients with peripheral artery occlusive disease (PAOD) for mapping of autogenous saphenous veins before femorodistal graft surgery for limb salvage and to compare the results with duplex ultrasound (US) and intraoperative findings. Materials and Methods: 38 patients with PAOD (21 men, 17 women; mean age, 71 years [range, 44-88 years) with peripheral arterial disease underwent first-pass and steady-state MR angiography after a single injection of the BPCA Gadofosveset Trisodium on a 1.5 T whole body MR system. Institutional ethics committee approval and written informed consent were obtained. Steady state images were assessed by 1 reader in order to identify great saphenous veins and to determine venous diameters on axial MPR images at three levels: below the saphenofemoral junction(1), mid thigh(2) and 10 cm above the knee joint(3). Duplex ultrasound was performed by an independent reader providing diameter measurements at the same levels. In addition, vessel useability/non-useability (patency; diameter range: 4-8 mm/occlusion; diameter <4 or >8 mm) were determined intraoperatively by the vascular surgeon during subsequent femorodistal bypass surgery. Results: 38 patients with a total of 76 assessable legs were included. Mean venous diameters for MRA/US were 5.4±2.62/5.5±2.8 for level 1, 4.7±2.7/4.6±2.9 for level 2 and 4.4±2.2/4.5±2.3 for level 3, respectively, without significant differences between the modalities (p=0.24/0.81/0.52). Subsequent surgery was performed in 27/38 patients. A suitable saphenous vein was diagnosed in 24/24 and non-useability was diagnosed in 3/3 of the 27 patients based on MRA/US, respectively. Intraoperative assessment confirmed useability and non-useability in the 24 and 3 patients. In the latter, prosthetic grafts were alternatively used for reconstruction. Conclusion: Mapping of autogenous saphenous veins as an imaging adjunct to peripheral MRA with a BPCA is feasible without significant differences as compared to duplex ultrasound. It correctly allows selection of candidates for autogenous venous graft surgery and may replace time-intensive venous ultrasound in the preoperative work-up of patients with PAOD.


2.5 Evaluation of the long-term consequences of deep venous thrombosis using bloodpool enhanced MRI

Tim Leiner, MD, PhD1,2,4; Carsten Arnoldussen, MD1; Joachim E. Wildberger MD, PhD1,2,

Cees Wittens, MD, PhD3,; Michiel W. de Haan 1,2 Maastricht University Medical Center, Departments of Radiology1 and Vascular Surgery3 and Cardiovascular Research Institute Maastricht (CARIM)2, Department of Radiology,

Utrecht University Medical Center4

Purpose The postthrombotic sydrome (PTS) is a complex of symptoms that occurs as a long-term consequence after an episode of deep venous thrombosis. Traditionally, susptected PTS is evaluated with duplex ultrasonography (DU) but this imaging modality has well-known limitations in evaluating the entire peripheral venous system for the presence of postthrombotic changes such as long imaging times and suboptimal depiction of the infrapopliteal vessels. Methods Fifty patients with suspected PTS and were included in this study. All patients underwent first-pass contrast-enhanced MRA of the peripheral vascular tree from the diaphragm to the ankles followed by equilibrium-phase imaging to depict both the arterial and the venous system with ultra-high spatial resolution. Spatial resolution in the first pass varied between voxel sizes of 2.0-5.0 mm3, whereas in the steady state voxel sizes varied between 343 microns (0.7x0.7x0.7 mm) and 2.0 mm3. In addition to first pass imaging, all depicted named vessel segment were evaluated for the presence of intraluminal filling defects in the equilibrium phase. Results Thirty-five patients (70%) exhibited at least 1 intraluminal venous filling defect. In almost all of these patients this filling defect involved more than one venous vessel segment. None of the patiens had significant arterial stenoses. Peripheral venous abnormalities included long-segmented intraluminal filling defects in the central part of veins (so-called postthrombotic material), venous ectasias and deep venous thrombi. In addition, 15 patients had inferior vena cava involvement. Conclusions Combined blood pool MRA and MR venography is highly valuable for the evaluation of the entire lower extremity, pelvic and abdominal venous system in patients with suspected PTS and can be applied in clinical practice to accurately determine the presence of postthrombotic material.


2.6 Prevalence of deep venous thrombosis as detected by magnetic resonance thrombus imaging with a blood pool

contrast agent in patients with suspected peripheral arterial disease

Guido M. Kukuk, Dariusch Hadizadeh, Ute Fahlenkamp, Arne Koscielny, Frauke Verrel, Hans H. Schild, Winfried A. Willinek

Departments of Radiology and Vascular Surgery, University of Bonn, Germany Purpose: To assess the prevalence of deep vein thrombosis in patients with suspected peripheral arterial disease using blood pool contrast-enhanced MR angiography. Methods: After institutional review board approval and informed consent 243 consecutive patients (160 male; 83 female; mean age 65.1 ± 11.7, range 36-92) with suspected peripheral arterial disease (PAD) were included in this prospective study. PAD was clinically categorized into Fontaine stages 1 (n=39), 2a (n=25), 2b (n=76), 3 (n=23) and 4 (n=80). All MR examinations were performed on a 1.5 T whole body MRI scanner (Achieva; Philips Healthcare, Netherlands). First pass and steady state 3D-MRA datasets were acquired after a single intravenous injection of 0.03 mmol/kg body weight Gadofosveset Trisodium. Effective voxel sizes of steady state images were 0.88x0.88x1.50 mm³ (pelvis), 0.88x0.88x0.99 mm³ (upper legs) and 0.52x0.52x0.49 mm³ (lower legs). MRA images were analyzed by two radiologists in order to identify venous thrombosis. Acute deep vein thrombosis was defined as an increase in vessel diameter in combination with a total or subtotal filling defect. All patients diagnosed with acute deep vein thrombosis on MRA underwent color coded duplex sonography for confirmation within 24 hours. Results: Steady state MRA was successfully performed in 242/243 patients. In one patient the whole examination revealed non-diagnostic due to heavy motion artifacts. In 6 patients one or more venous segments were not clearly depicted due to motion or susceptibility artifacts caused by endoprothetic implants. Acute deep vein thrombosis was detected in 5/83 (6.0%) female and 4/159 (3%) male patients. Overall prevalence of acute deep vein thrombosis was 3.7% (9/243). Duplex sonography confirmed the diagnosis of venous thrombosis in all 9/9 patients (100%). Venous thrombosis was present in 4 patients with Fontaine stage 1 PAD, 1 patient with stage 2b PAD, 1 patient with stage 3 PAD and in 3 patients with stage 4 PAD, respectively. The 9 patients underwent immediate antithrombotic therapy. Conclusion: Venous thrombosis as detected by magnetic resonance thrombus imaging with a blood pool contrast agent was prevalent in 3.7% of patients with suspected peripheral arterial disease. Magnetic resonance venous thrombus imaging as an adjunct to MRA of the peripheral arteries adds clinically and therapeutically relevant information of “mixed” arterial and venous disease and may play an important role in the risk stratification of patients with suspected peripheral arterial disease.


2.7 Imaging of thromboembolic disease with MRA/MRV Aschauer M.A.,ElstnerJ.,Obernosterer A., Univ. Hospital. GRAZ, Austria

INTODUCTION/BACKGROUND: Pulmonary embolism (PE) and deep venous thrombosis (DVT) are individual manifestations of a single entity: Venous thromboembolic disease (VTE). The gold standard (GS) for imaging in thromboembolic disease (for extremities direct venography with injection of potential nephrotoxic iodinated contrast medium (ICM) in the foot/hand/arm/selected vein) is time consuming and often not all lower leg veins fill with contrast and/or the mixture with not contrast enhanced blood e.g. from the internal iliac vein or the common iliac vein from the other leg can be a problem. For PE diagnostic with CT there are known limitations and draw backs: large amount of possible nephrotoxic ICM is needed, the radiation dose is high (600 fold of chest x- ray) and the visibility of thrombi in the lower legs is bad (nevertheless Vv. fibulares show diameter of 8-10 mm- this is relevant for therapy management especially in patients with acute or chronic PAE). MATERIAL AND METHODS: Between 2006 and 2010 we prospectively included 559 patients (289 f/270male) with suspected PAE/ THROMBOSIS. We performed a one stop shop MRA of pulmonary arteries and MR venography (MRV) in the same session using 1,5 TESLA Siemens SYMPHONY with surface coils , i.v. injection of Gadofoveset® 0.03 mmol/kg (blood pool agent). Gradient echo sequences with very short TR /TE and low flip angels allowed the quickest examination within 20 min all in one. RESULTS: More than 90 % examinations had a very good or good image quality in both parts (MRA, MRV) with a high diagnostic confidence. In all patients the visibility of the pulmonary trunk and the right and left main PA was good or excellent, also in patients with no breath hold capability. Pleural effusions, infarct pneumonia and peripheral perfusion defects as well as signs of pulmonary hypertension and right heart insufficiency were also useful parameters for staging of VTE. In patients with proven PE more than 50% showed thrombi in the venous system within the common femoral vein or proximal of this region (where especially duplex sonography is limited). Sometimes cause of VTE could be seen: tumour of e.g. kidney, liver, testis, pancreas, baker cyst or vascular anomalies and malformations. No patient showed NSF up to now – no patient had a CIN after contrast media injection including these with impaired renal function at the beginning of the examination. The brest feeding woman showed excretion in the milk comparable to the Magnevist®excretion in the literature. CONCLUSION: MRA/ MRV is a useful method in detecting PE and DVT, especially in patients when radiation dose and contrast induced nephropathy seem to be a major problem. Further studies are needed to compare the role of MRA/MRV with CT regarding the sensitivity and specificity of both methods in order to allow the change of the (clinical) gold standard (despite some centres use catheterangio as GS).


Fig. 1. The conventional FSD module

Fig. 2. Two FSD modules are integrated in

a.

Fig 3. Phantom subtraction MIP obtained using FSD1(a) and FSD2 (b) sequences.

Fig. 4 Fig. 5

Fig 4 and 5. FSD2 (b) depicted more conspicuous segments than FSD1 (a), as marked by arrows

2.8 Noncontrast MRA of the hand using mutli-directional flow-sensitive dephasing preparation

Fan Z1.2, Hodnett P1, Davarpanah A1, Scanlon T1, Sheehan J1, Carr J1, Li D1,2

1. Radiology, Northwestern University, Chicago, IL, USA 2. Biomedical Engineering, Northwestern University, Evanston, IL, USA

Purpose: In previous noncontrast hand MRA studies using ECG-triggered 3D bSSFP with flow-sensitive dephasing (FSD) preparation [1], flow-sensitizing gradient pulses applied in both readout (RO) and phase-encoding (PE) directions simultaneously renders the flow-sensitivity of the FSD module to be a single direction, as derived from the vector sum of the FSD gradients (Fig. 1). In this work, we proposed a new FSD preparative module for multi-directional flow. Methods: - Pulse sequence The new FSD module consists of two FSD sub-modules with the gradient pulses applied along the RO direction only in the 1st module and along the PE direction only in the 2nd (Fig. 2). - Flow phantom study Gd-doped water was pumped (flow rate: 15 cm/s) through a silicone tube (4.8-mm ID). Two perpendicular segments of the tube were immersed in a water bath and imaged on a 1.5T MR system (Espree, Siemens). A conventional one-module FSD sequence (FSD1) (Fig. 1) and the two-module FSD sequence (FSD2) (Fig. 2) were used for 3D MRA. - Volunteer study (12 healthy subjects, 1 patient with secondary Raynaud’s phenomenon). Prone position with hands above the head. Two noncontrast MRA scans (FSD1 and FSD2, the order was randomized) preceded a high-resolution CE-MRA scan (0.15 mmol/kg bodyweight Magnevist injected at 2 ml/s) at 1.5T. - Image analysis Reviewed by two blinded radiologists, vessel conspicuity (score: 0-3) was assessed for 15 segments per hand on MIP MRA obtained using FSD1 and FSD2. To compare FSD2 with CE-MRA, overall image quality, venous contamination, motion degradation, and vessel conspicuity were assessed using the methods described in [2]. Whether a digit could be visualized to the terminal third was recorded. Results: FSD1 vs FSD2 Flow phantom images showed that the FSD1 module is only sensitive to the flow coinciding with the vector sum of the FSD gradients, whereas the FSD2 module has no this limitation (Fig. 3). As expected, certain signal loss on MIP images in some segments were observed with FSD1, which was markedly improved with FSD2 (Fig. 4, 5). Vessel conspicuity: in 9 segments of the right hands (RH), FSD2 outperformed FSD1; in 9 segments of the left hands (LH), FSD2 outperformed FSD1. FSD2 vs CE-MRA Segments visualized: 211/270 vs. 178/270. Vessel conspicuity: comparable except for 4 segments in the RH and 1 segment in the LH. Terminal third visualized: 47/72 vs 3/72. Other assessments are omitted here. Conclusions: The new FSD module can reliably suppress multi-directional blood flow and enable comparable vessel delineation with CE-MRA. References: 1. Sheehan J et al. ISMRM 2009 (#423). 2. Lim RP et al. Radiology 2009; 252:874-81.


2.9 The Canadian Atherosclerosis Imaging Network – A Frame Work for Pan-Canadian, Multi-modality Vascular

Imaging Studies Richard Frayne, PhD for the CAIN Investigators (www.canadianimagingnetwork.org)

University of Calgary and Seaman Family Centre, Calgary, Alberta, Canada Purpose: The Canadian Atherosclerosis Imaging Network (CAIN) is a collaborative group of investigators, first brought together in 2007, with the objective of furthering Canada’s capacity for clinical vascular imaging research. It is a novel, national research network, combining in vivo imaging of vessel wall and subsequent end-organ (i.e., brain and heart) disease with relevant clinical and pathological endpoints. Its members bring together essential technical and clinical expertise, particularly in the areas of the imaging of carotid and coronary disease, heart and brain. Methods: The premise behind CAIN is that atherosclerotic disease is systemic and that our understanding would be enhanced from systematic, multicentre, and multi-modal investigations. The Canadian Institutes for Health Research funded the network’s inception in 2008. Additional funding for CAIN has been secured from the Canada Foundation for Innovation for networking and other key elements of imaging infrastructure, as well as from pharmaceutical partners, via ongoing support for clinical trials. The specific foci of CAIN are: 1) technology development, 2) clinical translation, and 3) clinical-research training. Technology, Translation and Training - these are the three “T’s” that underlie our projects. The projects, themselves in turn, are built upon integrated but distributed data and knowledge transfer systems, and common research protocols and platforms that link the Core Sites (Montreal, Calgary, London, Ottawa, Toronto) and the Clinical Partner Sites. The three initial CAIN projects are: 1) vascular biology of atherosclerotic plaque, via carotid artery imaging with MR, 2) vascular imaging technology development and assessment, comparing 3D ultrasound of carotid artery disease to post-endarterectomy specimen pathology, and 3) translation to clinical research and clinical practice, comparing intravascular ultrasound of coronary arteries to 3D ultrasound of carotid arteries. Sub-studies, many involving MR imaging of the vessel, heart and brain, have been proposed and approved. Results: CAIN has initiated each project and has begun recruitment at the Core Sites. Forty Clinical Partner Sites are been identified across Canada. A novel, distributed, analysis system has been designed and will be implemented in late 2010 that will utilize Canada’s existing CANAIRE network, allowing for fast and automated transfer of data to Montreal and between the five Core Sites. A Training and Transfer Program has been initiated for dissemination of our findings. Conclusions: CAIN will make Canada an international resource for studying atherosclerosis and novel therapeutic interventions, as it provides underlying systems for data and knowledge transfer, and links world-class expertise and motivation to undertake multicenter clinical trials.

CAIN Core Sites (yellow stars) and Clinical Partner Sites (white diamonds) as of 2010. Over 45 centers are participating in CAIN.

CAIN integrated network infrastructure linking the Core and Clinical Partner Sites to patients.


3.1 Hemodynamic Assessment of Abdominal Aortic Aneurysm with Use of Three Dimensional Cine Phase

Contrast Image and Flow Analysis Application Yasuo Takehara1, Haruo Isoda2, Hiroyasu Takeda1, Marcus Alley3, Roland Bammer 3, Takashi Kosugi 4, Toshiyuki Shimizu 4, Masaya Hirano 5, Tetsuya Wakayama5, Naoki

Unno6, Norihiko Shiiya7, Harumi Sakahara 1

1 Radiology, 6 Vascular Surgery and 7 Cardiovascular Surgery, Hamamatsu University School of Medicine, Hamamatsu Japan, 2 Radiological Technology, Nagoya University School of Health Sciences, Nagoya, Japan, 3 Radiology, Stanford University School of

Medicine, Stanford, USA, 4 R’s Tec. Co., Hamamatsu, Japan and 5 GE Healthcare Japan Co. Hino, Japan,

Purpose：To assess the hemodynamic behavior including wall shear stress (WSS) and oscillatory shear index (OSI) of the abdominal aorta affected or unaffected by the aneurysm using time-resolved 3D phase-contrast MRI (4D-Flow) post-processed by our application “Flova” (flow visualization and analysis, R’s tech, Japan). Materials and Methods：Twenty consecutive patients with abdominal aortic aneurysm (AAA) were recruited and underwent MRI using 1.5T Signa TwinSpeed with Excite. Before 4dflow, time resolved Gd3DMRA was performed. Then, ECG gated resp-compensated 4D-Flow (parameters: TR/TE/FA/NEX of 4.3/1.7/15/1, FOV of 30 cm, 256x160, 4mm th., 28 partitions, 20 phases during one cardiac cycle, imaging time of 20 min). VENC was optimized based on the values measured with 2D PC cine. The flow velocity data derived from 4D-Flow and the geometric data of the boundary of the aortic wall determined by Gd3DMRA were interpolated, and we could measure the WSS of the abdominal aorta and overview the change of WSS related to cardiac cycle as color maps. Result：The WSS of the abdominal aortic aneurysm was significantly lower (less than 1.5 Pa) than that of non-aneurismal wall near the aneurysm (over 1.5 Pa) in all patients. The OSI of the aneurismal wall was significantly higher than the unaffected segment reflecting turbulent and vortex flow. Conclusion: The WSS of AAA was significantly lower, OSI higher than that of unaffected segment, which may reflect that the aneurismal wall is continuously affected by the risk of aneurismal growth and future risk of rupture.


3.2 7D PC MRI to study Helical Blood Flow in the Human Aorta

Morbiducci U. 1, Ponzini R.2, Rizzo G. 3,5, Cadioli M.4, Esposito A. 5, De Cobelli F. 5, Del Maschio A. 5 Montevecchi F. 1, Redaelli A. 6

1* Politecnico di Torino, Italy, 2 CILEA, Italy, 3 IBFM-CNR, Italy, 4 Philips Healthcare, Italy, 5 Scientific Institute H S. Raffaele, Italy, 6 Politecnico di Milano, Italy

Purpose Time-resolved 3D phase contrast MRI (7D PC-MRI) is the most advanced clinical image-based flow visualization techniques. It allows the acquisition of in-vivo quantitative volumetric dynamic maps of blood flow velocity, by which complex blood flow patterns can be studied both qualitatively and quantitatively. Aim of the study is the investigation of the haemodynamics within the aorta of five healthy humans in order better understands the complex helical flow patterns in this vessel, whose contribution to the primary circulation is still debated. For this purpose, we applied 7D PC MRI, joined with algorithms for advanced fluid dynamics, for the estimation of indices, which can synthetically and quantitatively characterize local topology of blood flow in terms of the alignment of the velocity and vorticity vector. Materials and methods We used 7D PC MR velocity mapping (MR Achieva 1.5T, Philips Medical Systems, The Netherlands) to investigate blood flow in the aortic arch of five healthy individuals. On this dataset, we applied a 4D descriptor - Helical Flow Index (HFI) - of the helical content of blood flow in vessels. HFI is a Lagrangian-based metric. Virtual particles were tracked in their evolution within the arterial lumen. Over those Np particles moving in the fluid domain, a mean quantity can be calculated as follows:

∑ ∑= =

•=

p kN

k

N

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Conclusion This study suggests that HFI has the potential for a full quantitative and qualitative description of the aortic flow features in healthy. References [1] Morbiducci et al, J Biomech, 40:519-534, 2007. [2] Morbiducci et al, Ann Biom Eng, 37:516-531, 200

Fig. 1: Evolution of the particle sets, emitted at phase 5, of two individuals. Color coding of particle traces in terms of LNH allows visualizing the local left/right handed rotation of trajectories.


3.3 4D Flow and Plaque Imaging in the Descending Aorta: Stroke Risk by Retrograde Embolization

M. Markl1, J. Simon2, S. Brendecke2, J. Bock1, R. Lorenz1, A. Harloff2 1 Radiology, Medical Physics, 2 Neurology, University Hospital Freiburg, Germany

Introduction: Complex aortic plaques (≥ 4mm thickness) are considered a major source of stroke1. Although their incidence is highest in the proximal descending aorta (DAo), such atheroma are usually not considered a potential source of stroke because retrograde embolization seems unlikely. However, there is growing evidence that diastolic retrograde flow in the DAo may be a frequent phenomenon in the presence of atherosclerosis and thus an overlooked mechanism of retrograde embolization2-4. An initial proof-of-concept study and a larger follow up trial in acute stroke patients were conducted to investigate the incidence of retrograde flow from complex DAo plaques and its role as a new risk factor for embolic stroke5,6.

Methods: In a pilot study, 63 patients with acute stroke were prospectively assessed (2006-2007) to evaluate the incidence of high risk plaques and the extent of retrograde flow in the DAo5. Subsequently, a consecutively recruited patient cohort (94 acute stroke patients, 2008-2009) was examined using an improved MRI protocol6. In all patients, contrast enhanced MRA and T1-weighted 3D bright blood GRE (resolution ~1mm3) were performed to localize complex plaques in the thoracic aorta. Flow-sensitive 4D MRI (spatial / temporal resolution = ~2mm3 / 41ms) was employed to measure time-resolved 3D blood flow within the aorta7. 3D flow visualization using time-resolved 3D particle traces was used to determine the extent of diastolic retrograde flow in the descending aorta. In the follow up study, data analysis also included co-registration of plaque location and 3D blood flow to assess the stroke risk associated with the individual plaque.

Results: Substantial descending aortic retrograde flow was found for the pilot (26.2 ± 12.3 mm) and follow-up (26.6 ± 12.1 mm) study. An indirect comparison of plaque location and extent of reverse flow in the pilot study demonstrated retrograde flow connecting plaque and left subclavian artery in 60.6% of patients with complex plaques ≥ 4mm. The direct evaluation of retrograde flow originating from each individual atheroma in the follow-up study revealed that retrograde flow from complex DAo plaques reached the left subclavian artery in 59%, the left common carotid artery in 24%, and the brachiocephalic trunk in 14% of patients (see figure 1). In both studies, retrograde embolization constituted the only probable source of stroke in a substantial fraction of patients with previously undetermined stroke etiology (20% and 24%). Aortic valve insufficiency was rare and did not correlate with retrograde flow.

Discussion: The proof-of-concept study (n=63) and the direct evaluation of flow originating from complex DAo plaques (n=94) demonstrated a high incidence of retrograde flow from DAo plaques to the brain feeding arteries which could explain embolism to all brain territories. These findings suggest that complex DAo plaques should be considered a new high risk source of stroke. Fig. 1: Cumulative results of the follow-up study in 94 acute stroke patients. Image fusion of a 2D slice showing a detected complex plaque (>4mm) in the proximal DAo (yellow arrow) with flow-sensitive 4D MRI data. 3D particle traces emitted at the site of the atheroma illustrate the formation of retrograde flow for three successive diastolic time frames. A direct connection of plaque location and retrograde flow reaching all three supra-aortic branches can be clearly appreciated indicating the potential for retrograde embolization and stroke risk in all brain territories.

References: 1. Kronzon I, Tunick PA. Circulation. 2006;114:63–75. 2. Svedlund S, et al. Cerebrovasc Dis. 2009;27:22–28 3. Bogren HG, et al. J Magn Reson Imaging. 2004;19:417– 427. 4. Harloff A, et al. J Magn Reson Imaging. 2007;26:1651–1655. 5. Harloff A, et al. Stroke. 2009;40:1505–1508. 6. Harloff A, et al. Stroke. 2010; published online. 7. Markl M, et al. J Magn Reson Imaging. 2007;25:824–831.


3.4 4D Pressure Difference Mapping in the Aorta J. Bock1, R. Lorenz1, A. Harloff2, M. Markl1

1Radiology, Medical Physics and, 2Neurology, University Hospital Freiburg, Germany

Introduction: Time-resolved 3-directionally encoded phase contrast 3D MRI techniques (flow-sensitive 4D MRI) [1] can be used for the analysis of vascular hemodynamics with complete coverage of entire vascular segments such as the thoracic aorta. In addition, the comprehensive anatomic and flow information in such data sets can be used to derive additional functional parameters such as the spatio-temporal distribution of pressure gradients inside the vascular lumen. It was the purpose of this study to apply 4D pressure difference mapping in a cohort of normal volunteers and to evaluate pressure differences changes associated with aortic pathologies (atherosclerosis, coarctation). Methods: All measurements were performed on a 3T system (TRIO, Siemens, Germany) using an ECG gated and respiration controlled rf-spoiled gradient echo sequence. Flow sensitive 4D MRI (spatial / temporal resolutions ≈ 2x1.7x2.4 mm3 / 40.8 ms, venc = 150 cm/s) in the thoracic aorta was performed in 12 volunteers (age = 24.5y), 3 patients with severe aortic atherosclerosis (aortic plaques > 4 mm as demonstrated by TEE, age = 73.3y), and 6 patients after repair for aortic coarctation (age = 23y). To segment the aortic lumen a previously reported processing chain including time- averaged PC-MRA calculation and flood filling algorithm was used [2]. The segmented lumen was used in conjunction with the 4D velocity data to estimate pressure differences according to the Navier-Stokes equation [3, 4]. For validation, a stenosis model was connected to a pump with constant flow. The expected pressure gradient across the model stenosis according to Bernoulli was compared to the calculations using MR velocity data. For in-vivo quantitative analysis, 2D planes were placed at different anatomical landmarks. In patients with coarctation results were compared to available findings from Doppler ultrasound. Results and Discussion: Pressure gradients calculated for the well defined conditions in the stenosis model show good agreement between Bernoulli and Navier-Stokes approaches (8.1 mmHg vs. 7.4 mmHg, respectively). Figure 1 shows in blue color mean pressure differences averaged over 12 volunteers in 5 aortic analysis planes. High systolic pressure differences and the reflected pressure wave (inverted pressure difference during early diastole) were clearly visible in all volunteers. The patients’ data (in black, averaged over 3 patients with atherosclerosis) demonstrated similar peak pressure differences but clearly showed altered pressure dynamics and an earlier inversion of the pressure wave. These findings correspond well to the expected increased aortic stiffness associated with atherosclerosis and thus increased pulse wave velocity and earlier reflection at the periphery. The applied approach demonstrates the potential to derive quantitative information such as 4D pressure gradients from flow sensitive 4D MRI velocity data. In patients with coarctation MRI based mean pressure gradients correspond well to the pressure gradients calculated using peak velocity measured in MRI, but underestimated the pressure gradient compared to echocardiography. In summary, comparison of volunteer and patient data demonstrated the sensitivity of the method for the detection of altered magnitude and dynamics of pressure differences in the presence of disease. References: [1] Markl M, JMRI 2007; 25 [2] Bock J, Proc ISMRM 2009; p3849 [3] Tyszka M, JMRI 2000; 12[4] Ebbers T, MRM 2001; 45

Fig. 1: Time-resolved mean pressure differences in 5 analysis planes; blue line: averaged over 12 volunteers; black line: averaged over 3 patients with plaque in the aorta

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3.6 Hemodynamic features of the cerebral dural sinuses demonstrated by PC VIPR MRV

Ben Landgraf, Warren Chang, Michael Loecher, Yijing Wu, Steven Kecskemeti, Kevin Johnson, Aaron Field, Oliver Wieben, Charles Mistretta, Patrick Turski

Departments of Medical Physics and Radiology, University of Wisconsin, Madison, WI Introduction : Venous outflow obstruction has been implicated as a cause of increased intracranial pressure. Frequently, patients undergo invasive catheter based transvenous measurements of pressure gradients to determine the magnitude of the flow restriction. Some authors propose that venous stenting should be considered when the pressure gradient is greater than 10 mmHg. We have developed and clinically implemented a method to measure pressure gradients within the dural sinuses based on velocity data acquired using a highly accelerated 3D Radial Phase Contrast MRA technique (PCVIPR). Methods: PCVIPR data were acquired in ten normal volunteers and patients with venous outflow obstruction. PCVIPR datasets were reconstructed as magnitude images for anatomical assessment. To reliably achieve high quality images, several automated correction schemes were applied to account for the effects of T1-saturation, trajectory errors, and aliasing associated with undersampling. Typical scan parameters were: 62.5 kHz receiver bandwidth, 0.67-0.85 mm isotropic spatial resolution in less than 5 minutes, imaging volume: 32x32x32 cm, VENC of 80-100 cm/s. Cardiac gating was performed retrospectively with a temporal ‘view sharing like’ filter for radial acquisitions. Data processing was accomplished in customized analysis and visualization tools (Matlab and Ensight). Pressure gradients in the sinuses were calculated using the Navier-Stokes equation based on the cine velocity vector fields as measured by PCVIPR using an iterative algorithm. Results: PCVIPR data sets were successfully acquired in all subjects. In the normal subjects the average pressure gradient from sagittal sinus to the transverse sinus was 3.5 mmHg. The average pressure drop from the transverse sinus to the sigmoid sinus was 2.8 mmHg and from the sigmoid sinus to the internal jugular vein was 2.8 mmHg. In the figure below we show the clinical utility of this technique in a patient with Idiopathic intracranial hypertension. Note the marked increase in velocity and severe pressure gradient across the segment of venous stenosis.

Conclusions: Pressure gradients in the dural sinuses can be measured non invasively using highly accelerate 3D PC MRA velocity data. We are extending this investigation to measure dural sinus pressure gradients in a larger population of patients with venous outflow obstruction. References [1] P Zamboni et al, Int Angiol, 2010, [2] A Donnet et al, Neurology 2008, [3] Tyszka et al, JMRI 2000


Fig.1: 3D Streamline visualisation of the aorta in part 1 and the superior sagittal sinus in part 2. The improvement of streamline visualization from uncorrected data a) to corrected data (2nd order eddy currents with additional correction for gradient non-linearities) b) is clearly visible.

3.7 Correction methods for streamline visualization in the aorta and the superior sagittal sinus of healthy volunteers

R. Lorenz1, J. Bock1, J. G. Korvink2,3, M.Markl1 1Medical Physics, Dept. of Radiology, University Hospital Freiburg, Germany,

2Freiburg Institute for Advanced Studies (FRIAS) and 3Dept. of Microsystems Engineering, University of Freiburg, Germany

Purpose: The visualization of time resolved 3D phase contrast data is an important tool for the analysis of flow characteristics inside the vessels of interest [1]. However since measurements rely on velocity induced changes in the signal phases, PC-MRI is very sensitive to phase offset errors such as eddy currents [2], Maxwell terms [3] and gradient field non-linearities [4]. All three effects can severely distort the measured three-directional velocities (Vx, Vy, Vz) and thus result in distortion of streamlines which might lead to incorrect flow pattern visualization and subsequently to false conclusions regarding flow characteristics. In this study correction methods for these phase offset errors were applied to 3D phase contrast in vivo data (healthy volunteers: aorta, superior sagittal sinus) to systematically evaluate and quantify their effect on 3D flow visualization based on streamlines. Method: All experiments were performed on a 3T MR system (Siemens MAGNETOM Trio, Germany) using a time resolved 3D phase contrast MRI pulse sequence with three-directional velocity encoding. Imaging parameters for all experiments were: aorta: venc: 1.5m/s, res.: 2.0 x 1.7 x 2.2mm3, FOV: 320 x 240mm2; superior sagittal sinus: venc: 0.4m/s, res: 1.4 x 1.1 x 1.1mm3, FOV: 220 x 206mm2. Three different correction methods were applied to the acquired flow data 1): For 1st order eddy current correction a plane was fitted to static tissue in a least square sense to determine and subtract a linear phase drift and offset from the phase contrast data. 2): For 2nd order eddy current and Maxwell correction a 2nd order polynomial fit was adapted to the static tissue to subtract the 2nd order phase evolution from the phase data. 3) Effects of gradient field inhomogeneities were corrected by calculating the relative field deviations according to vendor specific gradient field model of the three-directions in each voxel. 3D visualization (EnSight, CEI, NC, USA) was used for comparison of 3D flow characteristics for the different correction methods. A home built tool (Matlab, The Mathworks, USA) was used for lumen contour segmentation and quantification (streamline counts) within the vessels.

Results: By applying the correction methods to the in vivo data streamline visualisation could be improved qualitatively (see figure). For qualitative investigation a streamline count was performed over all time frames and is given in percent from the total number of emitted streamlines: 2.9% / 0% (aorta / superior sagittal sinus) for uncorrected data, 2.5% / 5.4% for the 1st order eddy current correction, 3.0% / 8% for the 2nd order eddy current correction and 3.5% / 7.2% for additional correction for gradient non-linearities. Streamline distortions and improvements after correction were much more pronounced for the intracranial venous flow (almost complete loss of stream-lines before correction) compared to the aortic data. A substantially lower venc and thus stronger velocity encoding gradients for the cranial data resulted in increased eddy current and Maxwell effects. Conclusion: The results of this study clearly demonstrate the importance of correcting for the three major sources of gradient field distortions

for 3D visualization of 3-directional MR velocity data. It is important to note that such phase offset errors exhibit a substantial and non-linear increase with increasing distance from the isocenter in particular for 3D PC-MRI with large anatomic coverage. References: [1.] Buonocore MH, MRM 1998;40(2):210-226, [2.] Walker PG, et al. JMRI 1993;3(3):521-530, [3.] Bernstein MA, et al. MRM 1998;39(2):300-308, [4.] Markl M, et al. MRM 2003;50(4):791-801


4.1 How accurate are CE and TOF MRA at high field strengh (3.0.T) in assessing morphology and size of reperfusion of

cerebral aneurysms after endovascular coiling U.Wiesspeiner, R.Vollmann, M.Augustin, F.Ebner

Introduction Incompletely coiled aneurysms have an increased risk of rehemorrhage which requires long term follow up angiography (Stroke 2009). Selective DSA means to patients the need for repetitive invasive procedures and high radiation dose. The aim of the present study was to proof the accuracy of 3.0.T MRA in the follow up of cerebral aneurysms after endovascular coiling. Patients and Methods Forty-one patients (24 female, 17 male, mean age: 54 years) with previously coiled intracranial aneurysms underwent 3.0T MRA and DSA within a time period of 3 months.The study was performed on a Siemens TimTrio system. The MR imaging protocol included time-of-flight(TOF)-MRA (TR/TE/α: 22 3.68/ 18° , TA: 04:19 min) and contrast enhanced (CE)-MRA (FLASH 3D TR/TE/α: 3.74/ 1.49/ 20°;GRAPPA, Accel.Factor:2; TA: 00:22 min). Selective DSA was performed on a Siemens biplanar Neurostar system. Source images, maximum intensity projection, and volume rendering reconstructions were used for MRA evaluations, which included the state of the coiled aneurysms (complete occlusion/ morphology and size of aneurysm remnant/ reperfusion) and assessment of newly developed/ de novo aneurysms. Findings were assigned to 1 of 5 categories: exact match between MRA and DSA (1), minimal discrepancy in size or shape (2), moderate discrepancy (3), considerable discrepancy (4), no match between the findings of MRA and DSA. All images were analyzed retrospectively by 4 neuroradiologists. Results Complete occlusion: CE-MRA was correct in 14 of 14 cases. Aneurysm remnant/ reperfusion: CE-MRA was positive in 31 cases versus 29 cases in DSA. De novo aneurysms: TOF MRA depicted incidental new aneurysms in 15 patients (size from 1-5mm). DSA only verified in 11/15 cases the presence of an aneurysm; the diameter of aneurysms not verified on DSA was less than 3mm. Discussion In the current series the accuracy in assessing complete occlusion was 100%. False positive results in the MRA concerned only aneurysms/ remnants below 3mm in maximum diameter, which require no therapeutical intervention. From our data we conclude, complete occlusion and reperfusion of coiled aneurysms can be delineated by MRA with high confidence. So we suggest that MRA at 3T has the potential to replace DSA for the long term follow up of patients after endovascular coiling.

Key words: MRA at 3.0 T, cerebral aneurysm, endovascular coiling


4.2 New Natural History Findings Utilizing MRA for the Study of Intracranial Aneurysms

John Huston, Robert Brown, Matt Bernstein and Steve Riederer Mayo Clinic Rochester, Minnesota

Purpose: To update the findings of utilizing MRA to determine the natural history of sporadic and familial unruptured intracranial aneurysms. Background/Methods: Intracranial aneurysms are common with autopsy and imaging studies reporting frequencies of aneurysm detection of 1 – 9% and 1 – 2% respectively. The majority of aneurysms do not rupture but they are responsible for 80% of subarachnoid hemorrhage (SAH) cases which have a mortality of between 80 – 90% for severe SAH and between 10 – 30% for mild to moderate SAH. The International Study of Unruptured Intracranial Aneurysms (ISUIA) has determined that based upon clinical follow-up, the 5 year cumulative rupture rates for aneurysms in the anterior circulation are 0%, 2.6%, 14.5% and 40% for aneurysms less than 7 mm, 7 – 12 mm, 13 – 24 mm and 25 mm or greater in maximum diameter respectively compared with rates of 2.5%, 14.5%, 18.4% and 50% respectively for the posterior circulation. However, because ISUIA is based upon clinical not imaging follow-up, the rate of aneurysm enlargement was not determined. Results: Serial MRA exams of 165 patients with 191 aneurysms over a median follow-up period of 47 months demonstrated a frequency of enlargement of 6.9%, 25%, and 83% for aneurysm <8 mm, 8 – 12 mm and ≥ 13 mm respectively. In the Familial Intracranial Aneurysm Study (FIA), individuals with a family history of aneurysms demonstrated a rupture rate of 1.2% per year which is approximately 17 times higher than the rupture rate for subjects in ISUIA. In addition, FIA demonstrated that variants on chromosome 8q and 9p are associated with the presence of an aneurysm and that the risk of an aneurysm in patients with these variants is greatly increased with cigarette smoking. The use of MRA to determine morphologic changes in a large cohort determined that aneurysm enlargement occurred in 1 of 10 aneurysms and that larger size, particularly a diameter ≥ 8 mm, was predictive of future enlargement. Even small aneurysms carry a clinically relevant risk of enlargement. In a previously study with fewer aneurysms and a shorter period of follow-up, we reported a frequency of enlargement of 7% and that a diameter ≥ 9mm was a substantial risk factor for growth. However, whereas no aneurysm < 9 mm enlarged in the earlier study, we now report that 6.9% of aneurysms < 8 mm enlarge. Conclusion: These data suggest that serial MRA monitoring of aneurysms should be considered for all patient with a conservatively managed aneurysm and those with larger aneurysms should be imaged more frequently. References: ISUIA Investigators, NEJM 339:1725-1733, 1998 Phan, J Neurosurg 97:1023-1028, 2002 ISUIA Investigators, Lancet 362:103-110, 2003 Brown, J Neurosurg 108:1132-1138, 2008 Burns, Stroke 40:406-411, 2009


4.3 Stability of vascular centerlines and peak tortuosity measurements

Karl Diedrich, John Roberts, Richard Schmidt, Dennis Parker, University of Utah, UT, USA

Purpose Three dimensional medical imaging techniques such as Magnetic Resonance Angiography (MRA) can be used to diagnosis and evaluate vascular diseases. Tortuosity measurements of centerline representations of vascular trees can potentially assist in identifying vascular disease. Increased arterial tortuosity of arteries has been linked to cancer [1][2] and aging [3]. Decrease in number of arteries has been linked to hypertension [4]. Variation in tortuosity measurements within a patient can be due to variation in MRA data itself, the centerline algorithm and the segment of the centerline selected for the tortuosity measurement. Methods Most centerline algorithms start by segmenting the blood vessels and developing the centerline tree as a branching structure from a single root point of the vascular tree and the choice of the root point influences the construction and geometry of the centerline tree. By seeding the centerline algorithm at many different start points we have observed that some segments consistently are identical (stable), while others vary depending on the root point (unstable). We developed a method to visualize and quantify stable and unstable centerline coordinates by seeding the centerline at N tip ends of brain vascular segmentations. The stability of a centerline coordinate is the fraction of N times the coordinate belongs to a centerline tree. The set of all coordinates was visualized by plotting the inverse stability score to highlight the unstable portions (figure 1). Results & Discussion Accuracy of centerlines was determined by measuring the difference between algorithm generated and known centerlines in phantoms and visualizing centerlines in MRA brain artery images. We compared the stability and accuracy in phantoms and MRA brain images between Distance From Edge (DFE), Center of Mass (COM), binary thinning and DFE weighted COM followed by Dijkstra's shortest path generated centerlines and selected DFE weighted COM algorithm for its combination of stability and accuracy (figure 1). The centerline was used as a basis to create a tortuosity curve of the artery measuring the 3-D Distance Factor Metric (DFM). DFM measures the length (L) along the centerline and divides by the distance between the ends of the centerline segment measured. Selecting different end points generates different tortuosity measurement values along the same centerline. By calculating the tortuosity at every point of the centerline we create a tortuosity curve that measures tortuosity at all points and use the peak of the curve to quantify the tortuosity (figure 2). Conclusion The combination of the DFE weighted COM centerline and the peak tortuosity of the curve made stable repeated tortuosity measurements for different images of the same subject and can distinguish tortuosities between subjects (figure 2). References [1] Bullitt, E. et al. Acad Radiol 12, 1232-1240 (2005). [2] Bullitt, E., Reardon, D.A. & Smith, J.K. Neuroimage 37 Suppl 1, S116-9 (2007). [3] Bullitt, E. et al. Neurobiol. Aging 31, 290-300 (2008). [4] Kang, C. et al. Hypertension 54, 1050-1056 (2009). Acknowledgments This work was support by NLM Grant: T15LM007124, and 1R01 HL48223, and the Ben B. and Iris M. Margolis Foundation.

Figure 1: Higherintensity for instabilityof DFE weighted COMcenterline.

Figure 2: DFM Tortuositycurves of 3 subjects includingrepeated measures for one.


4.4 Accurate aneurysm morphometry using variable view angle tilting acquisition and super-resolution reconstruction

MinOh Ghim1, Sang-Young Zho1, DongJoon Kim2, Dong-Hyun Kim1, 2 1Electrical and Electronic Engineering, 2 Radiology, Yonsei University, Seoul, Republic of

Korea Purpose Achieve higher accuracy in depicting aneurysm morphometry by using a variable view angle tilting (v-VAT) pulse sequence and a modified super-resolution reconstruction method. Methods Using a v-VAT pulse sequence, images are acquired we can get images as if they are viewed at different angles that are defined by the user. These user defined view angle images can be acquired by changing the amplitude of the view angle gradient in the original VAT sequence [1]. Partial volume can effectively be resolved with different view angle acquisitions especially on sphere-shaped objects such as an aneurysm. In the k-space perspective, v-VAT sequence acquires kz according to the view angle Gz gradient. Subsequently, the data sets acquired with v-VAT sequence can be reconstructed as a 3D image. By modifying the super-resolution algorithm proposed by Peled and Yeshurun [2], which is an image based iterative reconstruction algorithm, we can reconstruct high resolution images appropriately suited for v-VAT. Images were obtained on Siemens 3T scanner using an agar filled carotid artery aneurysm phantom made of wax. A spoiled gradient echo sequence was modified by incorporating the v-VAT sequence. Comparisons were performed against a conventional 3DFT GRE sequence. The number of view angles was set to 17 from -80º to 80º with 10º intervals. Results The acquired images using v-VAT pulse sequence are shown in Fig.1. v-VAT can be understood as acquiring images at different view angles as shown. We applied the modified super-resolution algorithm and reconstructed higher resolution 3D images as shown in Fig. 2. Reconstructed images using v-VAT showed comparable results as that of the standard 3DFT GRE approach. Additionally, since v-VAT is an image based recon approach, ringing effects that occur in FT based recon do not appear (solid arrow). However, susceptibility artifacts at the air-phantom interface at the top and bottom center of the phantom were worse for v-VAT (dot arrow). Figure 3 shows the wax phantom built for the experiments performed. In the figure on the right, the image shows a slice of the aneurysm reconstructed using our proposed approach. The image shows a clear description of the morphometry of the aneurysm using the v-VAT approach. For accurate depiction of the morphometry of small aneurysms, restricted field of view imaging is preferable. Using FT approaches, ringing effects can be hazardous when using limited number of phase encodes. Here, we used a v-VAT approach and a image based reconstruction algorithm to accurately depict aneurysm morphometry and reduce ringing artifacts. The approach relies on varying the view angle of the object. The method can be readily extended to support a panoramic view by combining with a radial view angle tilting readout sequence. Conclusion An image based reconstruction approach using a variable view angle tilting approach is described. The sequence can be useful for accurate description of small aneurysms. Acknowledgement KITF(7-2009-0079), MEST (2010-0016421). References [1] Cho et al., Med. Phys., 15, 1988 [2] Peled and Yeshurun, MRM., 45, 29-35, 2001

Figure 2. 3D rendered image of theaneurysm phantom. (a) 3D GREimage with ringing artifact (solidarrow). (b) v-VAT reconstructedimage. Susceptibility inducedartifact were introduced in v-VAT(dot arrow).

Figure 1. v-VAT images along thedifferent view angles (-80° to 80°, 10°interval).

Figure 3. (left) snapshot of the aneurysm phantom. (right) v-VAT reconstruction depicting the aneurysm


4.5 Velocity Fields In Intracranial Aneurysms Gabriel Acevedo-Bolton1, Vitaliy Rayz1, Monica Sigovan1, Loic Boussel1, Alastair Martin1,

Vibhas Deshpande2, Gerhard Laub2, and David Saloner1 1Dept of Radiology and Biomedical Imaging, University of California San Francisco, and

2Siemens Medical Systems

Purpose: Flow dynamics are important determinants of the evolution of morphology in vascular disease, and together with biochemical processes regulated at the cellular level, are determinant in aneurysm progression and rupture. This study was performed to investigate the extent to which in-vivo time-resolved MR velocimetry is able to define imprtant descriptors of intra-aneurysmal hemodynamics, and in particular to evaluate the impact of noise on the estimated velocity fields. Methods: MR velocity fields were determined in vivo in patients with known intracranial aneurysms. These studies were repeated in exact replica flow models of these geometries using pulsatile flow with input flow equivalent to that measured in vivo. Finally, numerical simulations were performed for the same geometric and hemodynamic flow conditions. The impact of noise on the measured flow parameters was studied by measuring the velocity fields while varying: voxel size, fluid T1, and VENC values. Results: In general, the velocity fields measured in vivo, in vitro, and predicted by CFD simulations were found to have strong qualitative agreement. However, sources of important quantitative error were identified that were not apparent by visual inspection. Importantly, substantial intravoxel veloctiy dispersion is masked by averaging over all magnetization components within the voxel. This can result in a significant error in estimation of velocities in several instances: 1. where there is rapidly varying velocity fields; 2. at vessel edges where there are low intralumnal velocities and partial voluming with adjacent tissue; and 3. in regions where the mean intravoxel velocity approaches the chosen VENC. Conclusion: Intravoxel velocity dispersion and the presence of noise can significantly degrade measured velocity fields. In measuring flow, care should be taken to set the VENC higher than two standard deviations of the noise above the expected peak velocity. Reducing the VENC can provide considerabley improved estimation of velocities at the lumen edge where this assessment is important to determine wall shear stress, although care must be taken to avoid aliasing in voxels adjacent to the edge.


Table 1. WSS and impact zone size between Growing aneurysms and Non-growing aneurysms

Time-averaged WSS (Pa)

WSS in systolic phase (Pa)

Size ratio 0.296±0.2080.276± 0.219

4.05± 2.243.37±1.44

2.29± 1.322.05±0.95



2.04± 0.621.88±0.56

3.07± 1.222.85±1.01

Non-growing aneurysms

Growing aneurysms



Size ratio 0.296±0.2080.276± 0.219

4.05± 2.243.37±1.44

2.29± 1.322.05±0.95



2.04± 0.621.88±0.56

3.07± 1.222.85±1.01

Non-growing aneurysms

Growing aneurysms

Impa

ct z

one

Who

le

aneu

rysm

WSS, wall shear stress. Size ratio, Size Ratio against whole surface area of aneurysmsThere was no statistically significant difference in any item between the two groups.

4.6 Magnetic resonance fluid dynamics of growing intracranial aneurysms

Haruo Isoda 1, Hisaya Hiramatsu2, Shuhei Yamashita3, Yasuo Takehara 3, Takehiro Naitoh 4, Takashi Kosugi5, Toshiyasu Shimizu5, Hiroyasu Takeda 3, Masaki Terada6,

Tetsuya Wakayama7, Marcus T. Alley8, Shigeru Miyachi4, Harumi Sakahara 1 1 Department of Radiological Technology, Nagoya Univ. Schl. of Health Sciences, Nagoya,

Japan, 2 Department of Neurosurgery, Hamamatsu University School of Medicine, Hamamatsu, Japan,3 Department of Radiology, Hamamatsu University School of

Medicine, Hamamatsu, Japan, 4 Department of Neurosurgery, Nagoya University School of Medicine. Nagoya, Japan, 5 Renaissance of Technology Corporation, Hamamatsu,

Japan, 6 Department of Radiology, Iwata Municipal Hospital, Iwata, Japan 7 GE Healthcare Japan Corporation, Hino, Japan, 8 Department of Radiology, Stanford

University School of Medicine, Stanford, USA. Purpose Hemodynamics, especially wall shear stress (WSS), is reported to be one of the most important factors affecting the initiation, growth and rupture of intracranial aneurysms [1-3]. The purpose of our study was to compare WSS and impact zone size between growing aneurysms and non-growing aneurysms based on magnetic resonance fluid dynamics (MRFD), Methods Nine growing aneurysms (diameter; 3.6 to 10.5 mm, 7.6 mm on average) and six non-growing aneurysms (diameter; 4.5 to 11.5 mm, 6.9 mm on average) followed for at least 16 months were included in this study. We performed 3D cine PC MRI [4] with the use of 1.5T GE MR scanner with commercially available head coil. We calculated WSS of these aneurysms using in-house software (Flow visualization and analysis; Flova) [5] and compared the difference in WSS and impact zone size between growing aneurysms and non-growing aneurysms. The impact zone was defined as the area with WSS greater than 2.0Pa in an aneurysm. Results Spatial- and time-averaged WSS of nine growing aneurysms and six non-growing aneurysm were 1.88N/m2 and 2.04N/m2, respectively (Table 1). The former was lower than the latter; however, there was no statistically significant difference between the two groups. There was no statistically significant difference in impact zone size between the two groups . Conclusions We compared WSS and impact zone size between growing aneurysms and non-growing aneurysms based on magnetic resonance fluid dynamics. There were no statistically significant differences between the two groups in this study. References 1.Shojima M, et al. Stroke 2004;35: 2500–2505, 2.Jou LD, et al. AJNR 2008;29:1761 –1767, 3.Boussel L, et al. Stroke 2008;39: 2997–3002, 4.Markl M, et al. J MagnReson Imaging 2003;17:499–506, 5.Isoda H, et al. Neuroradiology. 2009 Dec 5. [Epub ahead of print] PubMed PMID: 19967532.


Fig. 1 3 different aneurysms. Left: Surface rendering of aneurysm A in left internal carotid artery (ICA) shows excellent depiction of aneurysm and small branching vessel. Middle: Streamlines show circulation with aneurysm B, located in the right ICA and Right: velocity vectors within aneurysm C located at junction of the ICA with the middle and anterior cerebral arteries.

4.7 Accelerated 4D Phase Contrast Velocimetry of Intracranial Aneurysms

Steven Kecskemeti, Kevin Johnson, Yijing Wu, Patrick Turski, Oliver Wieben Departments of Medical Physics and Radiology, University of Wisconsin, Madison, WI

Introduction Recently we reported on the use of phase contrast (PC) stack of stars (SOS) [1] to provide three directional velocity encoding with high spatial resolutions over regions with larger in-plane fields of view compared to slab thickness. We have since used the improved spatial resolution to image and provide hemodynamic related measurements of intracranial aneurysms with sizes 4mm or less. This abstract reports our initial findings. Methods and Results PC SOS with cardiac gating and 5 pt velocity encoding [2] was used to examine 10 patients with intracranial aneurysms of sizes about 4mm or less. The in-plane FOV was 220x220mm with acquired resolution 0.43x0.43mm, while slab thickness and resolution varied from 30-40mm and 0.7-1.0mm. Additional parameters include TR=8.0ms, TE = 3.7ms, tip angle = 20, BW = 83.3 kHz. Exams were about 9 minutes and performed on a clinical 3T scanner ( Discovery MR 750, GE Healthcare, Waukesha, WI ) using a standard 8 channel receive only head coil.

We conclude that 4D cardiac gated PC SOS is a practical method to study flow and pathological conditions for intracranial aneurysms. We have found that the improved resolution reduces intravoxel dephasing, thereby permitting velocimetry in regions of turbulent flow or circulation. References: [1] Kecskemeti et. Al Proc 17th ISMRM(’08) 2907, [2] Johnson et. Al MRM 63:349-355(2010).


Fig. 2: Concept for scout imaging: 1D projections acquired at different time points in the cardiac cycle show different arterial signal enhancement.

Fig. 3: CMT venography can detect different pathologies in the deeper and superficial system (a). CMT arteriography was compared to DSA (b). Coronal and sagittal scout views visualized the main arterial structures in the periphery in less than 2min (c). (a) (b) (c)

5.1 Continuously Moving Table Venography and Arteriography Sandra Huff, Michael Markl, Ute Ludwig

Dept. of Radiology, Medical Physics, University Hospital Freiburg, Germany

Purpose To overcome the limited spatial coverage of standard techniques, this study addresses the combination of 2D axial Time-of-Flight (TOF) and Continuously Moving Table (CMT) acquisitions for peripheral venography and arteriography.

Methods CMT venography is based on an interleaved acquisition of two imaging slices symmetrically arranged around one saturation slice (Fig. 1). This set-up allows for simultaneous acquisition of images with saturated arterial and venous blood signals during a single table sweep (venous and arterial image set). Subtraction of venous

and arterial image sets and display of positive signal values only, yielded venograms with suppressed background signal. Subtracting vice versa resulted in angiograms. However, imaging slices are characterized

by different arterial signal enhancement depending on the acquisition time in the cardiac cycle (pulsatile flow effects). For suppression of pulsatile signal changes, the sequence design was extended for arteriography by repeated acquisition of central k-space for the arterial set (Fig. 1(*)). View sharing provided several arterial images per slice position and cardiac cycle and the image with maximum arterial signal was used for subtraction.

For arterial vessel scout imaging, signal variations owing to pulsatile flow were not prevented, but instead exploited for fast detection of arteries in the body (Fig. 2). To achieve this aim, CMT was used to acquire multiple 1D projections for each slice. Herein, vessel locations were found by evaluation of regional signal differences and autocorrelation analysis. Volunteer and patient studies with image grading were performed for

all CMT techniques and compared to ultrasound (US), digital subtraction angiography (DSA) and CE-MRA. Results and Conclusion Image grading in volunteer studies demonstrated the feasibility of CMT venography and arteriography to assess the peripheral vessel system in a single scan. Efficient suppression of background signal was achieved by image subtraction. Pulsatile flow effects in angiograms could be suppressed by view sharing. Findings in venograms and arteriograms (Fig. 3a/b) were in good agreement with US and DSA, respectively. Grading of coronal and sagittal views confirmed that the presented approach for fast vessel scout imaging allowed for a spatially seamless visualization of main arterial structures within a scan time of less than two minutes (Fig. 3c). Findings in scout images were in agreement with CE-MRA and DSA results.

0 50 100 150 200 250 300 3500

0.005

0.01

0.015

time point 1:0 50 100 150 200 250 300 350

0

0.005

0.01

0.015

time point 2:

Projection

Aorta

0 50 100 150 200 250 300 3500

0.005

0.01

0.015

time point 1:0 50 100 150 200 250 300 350

0

0.005

0.01

0.015

time point 2:

Projection

Aorta

vein

saturation slice

table motionartery

venous image set

arterial image set

+++ ...

(*)

vein

saturation slice

table motionartery

venous image set

arterial image set

+++ ...

(*)

Fig. 1: Acquisition scheme for CMT venography and


5.2 FERAL MR Angiography for Rapid, Quantitative Flow Imaging of the Peripheral Arteries

Robert R. Edelman1, Erik Offerman1, Christopher Glielmi2, Ioannis Koktzoglou1 1Department of Radiology, NorthShore University HealthSystem, Evanston, IL USA

2Siemens Medical Solutions, Chicago, IL USA Purpose: The purpose of this study was to test a new method, called Flow-Encoded RAster Line (FERAL) scanning, for rapid, quantitative flow imaging over the entire length of the lower extremity peripheral arterial tree. Methods: The study was approved by the institutional IRB committee. Volunteers and patients were imaged on a 32-channel 1.5 Tesla MR scanner (Avanto, Siemens Healthcare, Erlangen). First, non-contrast MRA was obtained using quiescent-interval single shot MRA (QISS) with 1mm x 1mm x 3 mm spatial resolution [1]. Next, ECG-gated FERAL MRA was performed by acquiring axial 1D phase-contrast data from the infra-renal aorta to the level of the ankles in approximately 8 minutes with 2-3mm slice thickness, 30-60 slices per station, and 9-15 stations. Temporal resolution ranged from 13-30ms; 30-50 phases were typically acquired at each level. Flow-encoding was through-plane (i.e. cranio-caudad) with velocity encoding sensitivities typically ranging from ~45cm/s at the level of the mid-calf to ~110cm/s at the level of the infra-renal aorta. FERAL MRA data was reformatted into a coronal plane and viewed as a cine series. Mean velocity, peak velocity, and time-to-peak maps were calculated. Flow velocity profiles determined from the FERAL MRA were correlated with standard cine phase contrast MRI at selected levels. Time-resolved (TWIST) and stepping table CE-MRA were also acquired in some cases. Results: Normal flow patterns were well visualized in the cine display of the FERAL MRA. Using a temporal resolution of 20ms, a smooth, symmetrical cranio-caudad progression of flow could be observed in healthy subjects. With vascular occlusion, ipsilateral delay of the pulse wave and reduced flow velocity were seen. Other abnormal flow patterns, such as jets through vascular stenoses and collateral flow around occluded segments were also demonstrated. Flow profiles were similar to those obtained using 2D phase contrast MRI. Figure 1 shows a comparison of QISS MRA with FERAL MRA in a healthy volunteer. There is

excellent anatomical correspondence of the vessel segments seen with QISS MRA and the mean velocity image from the FERAL MRA. As expected, the FERAL MRA primarily demonstrates vessels with cranio-caudad flow because of the through-plane direction of flow encoding.

Figure 1(a). QISS MRA.

Figure 1(b). Selected frames from time-resolved FERAL MRA. Image intensity is proportional to flow velocity in the cranio-caudad direction. Time between frames is 20ms. Far right frame depicts the mean velocity image.

Conclusion: FERAL enables the creation of time-resolved flow-encoded MRA with arbitrarily high temporal resolution. Scan times are short and the technique is insensitive to patient motion. Normal and abnormal flow patterns can be evaluated over the whole extent of the peripheral arteries. In addition to depicting flow abnormalities associated with vascular stenoses and occlusions, the method enables quantitative assessment of flow parameters such as pulse wave velocity. References: [1] Edelman et al. Magn Reson Med 2010; 63:951-958.

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5.5 Effective 5-station whole body contrast-enhanced MRA at 3T with reduced contrast dose, tourniquet thigh compression, and combined neurovascular coil

and body coil. S. Barry, G. Cunnane, N. O Mahony, M. Knox, R. Dunne, G. Boyle, A. Fagan,

J.F.M. Meaney. Centre for Advanced Medical Imaging

Purpose: MRA is an attractive candidate for whole body imaging. However, heightened concerns about MR contrast safety have promoted greater awareness of dosing considerations which can negatively impact on image quality but lower dose may also result in less venous enhancement within the calfs. The purpose of this study was to evaluate image quality in 5-station MRA with reduced dose of contrast agent (20cc Multihance), thigh tourniquets to reduce venous enhancement and use of neurovascular coil for the first location. Methods and Materials: 15 patients were studied. A neurovascular transmit-receive coil was used for signal transmission and reception for the first location, the body coil for the remaining 4 locations. Thigh tourniquets inflated to 50mmHg were employed throughout the scan. Contrast injection rate was tailored to the total scan time. Scan data was initiated for the 1st location using fluoroscopic triggering. Table movement between stations was 4secs. All 3D CEMRA images employed CENTRA, spatial resolution was 1.2mm3. Image quality (0= non-diagnostic, 4=excellent) and venous enhancement (0=none, 4=arteries completely obscured by overlapping veins). Results: All 15 patients completed the study. Image quality overall was 3.77. Despite the long scan time Grade 2 (moderate) enhancement was present within the calfs bilaterally in one patient and grade 1 venous enhancement (minimal) unilaterally in one patient only. High quality diagnostic images were obtained at all locations and no lower leg stations were graded as non-diagnostic. Conclusions: Despite the long scan time and low contrast dose, high diagnostic quality near-isotropic 1mm MRAs from skull base to ankles were obtained in all patients. Use of tourniquet compression ensured minimal venous enhancement within the lower station.


5.6 MultiMRA - Initial Experience of Single Dose Gadobenate dimeglumine for Compre-hensive MR Angiography of the Lower Limbs with Dynamic Calf, 3 Station Bolus Chase &

High-Resolution Extended Phase Imaging S.Chandramohan, G.Roditi - Glasgow Royal Infirmary, Scotland, UK

Purpose Current trends in contrast-enhanced MRA are towards lower dose imaging for clinical and economic reasons. Single dose (0.1 mmol/kg) Gadobenate dimeglumine with higher relaxivity than other standard extracellular space (ECS) agents has been validated for usual first pass 3 station bolus chase MRA (1). However, in many situations standard imaging does not suffice and dynamic calf station acquisitions are incorporated in ‘hybrid’ peripheral MRA protocols with particular value in critical lower limb ischaemia. Furthermore, high spatial resolution steady state imaging using a blood pool contrast agent (BPCA) can add information missed on first pass MRA while allowing simultaneous venous assessment (2,3 & 4). Gadobenate dimeglumine exhibits weak protein binding resulting in a longer vascular residence time compared to standard ECS agents, in some ways akin to BPCAs. Indeed, Anzidei, et al (5) successfully employed this in carotid MRA for high resolution steady state imaging. We set out to compare a comprehensive lower limb MRA protocol incorporating dynamic calf imaging, first pass 3 station and high resolution extended phase imaging all using single dose gadobenate dimeglumine to the same protocol using BPCA (gadofovest trisodium). Methods 10 consecutive patients referred for lower limb MR angiography with either claudication or critical limb ischemia were included in this pilot study. Images were acquired in 3 phases; initial dynamic MRA (TWIST, Siemens) of the infrapopliteal vessels was acquired using 3 ml of contrast, subsequently standard 3 station first pass MRA with 9 ml of contrast. This was immediately followed by imaging in ‘extended phase’ with high resolution acquisitions of the thigh and calf vessels during infusion of final 3 ml of contrast at 0.3 ml/sec followed by 30 ml of saline flush at the same rate (total 15 ml gadobenate dimeglumine). Images are compared to historical controls imaged with gadofosveset trisodium using the same sequences with evaluation of image quality for arteries and veins on a Likert scale and ROI measurements for CNR on steady state images. Results Images obtained with gadobenate dimeglumine are not different to those obtained with gadofovest trisodium in terms of image quality and CNR in this pilot study. Dynamic and first pass images are indistinguishable while high spatial resolution extended phase images are also comparable, of note is that extended phase imaging is prone to similar movement artefact as steady state imaging with BPCAs with restless patients. Conclusion MultiMRA single dose gadobenate dimeglumine comprehensive lower limb vascular imaging including dynamic acquisitions and extended phase imaging is comparable with homologous image quality to similar strategies with BPCAs that include high resolution steady state acquisitions. References 1. Diagnostic Performance of Gadobenate Dimeglumine and Gadopentetate Dimeglumine for Peripheral MRA: Multicenter Comparison with DSA - Leiner et al. Proceedings SMRM-ESMRMB 2010, 2. MR angiography with blood pool contrast agents. Bremerich J, Bilecen D, Reimer P. Eur Radiol 2007, Dec;17(12):3017-24., 3. Peripheral MR angiography with blood pool contrast agent: Prospective intraindividual comparative study of high-spatial-resolution steady-state MR angiography versus standard-resolution first-pass MR angiography and DSA. Hadizadeh DR, Gieseke J, Lohmaier SH, Wilhelm K, Boschewitz J, Verrel F, et al. Radiology 2008, Nov;249(2):701-11., 4. Venous MR imaging with blood pool agents. Roditi GH, Fink C. Eur Radiol 2009;18(Supplement 5):E3-E12., 5. High-Resolution Steady State Magnetic Resonance Angiography of the Carotid Arteries: Are Intravascular Agents Necessary? Feasibility and Preliminary Experience With Gadobenate Dimeglumine. Anzidei M, Napoli A, Marincola BC, Kirchin MA, Neira C, Geiger D, et al. Invest Radiol 2009;44(12):784-92.


5.7 A Timing Algorithm Strategy for pMRA Jeffrey H. Maki1, George R. Oliveira1, Gregory J. Wilson2

1 - University of Washington, Seattle, WA. 2 - Philips Medical Systems, Cleveland, OH.

Purpose Use a pre-existing database of contrast enhancement timing parameters to devise a simple methodology for optimizing peripheral MRA (pMRA) timing in terms of minimizing venous enhancement and achieving appropriate table propagation speed using only contrast arrival information provided by an initial time-resolved lower extremity dataset. Methods With IRB approval, timing data from 71 pMRA studies (112 extremities) performed using the two station timing bolus technique (1) were retrospectively evaluated for the following timing parameters: antecubital to aorta (AC-Ao), antecubital to foot (AC-F), aorta to foot (Ao-F), antecubital to lower ext venous arrival (AC-venous), and aorta to lower ext venous arrival (Ao-venous). Results Although there was a broad range of timing values among different patients, there was excellent correlation between AC-F and Ao-F times (R2 = 0.76 -graph). The Ao-F transit time represents the quickest the lower station can begin (after upper station) without “outrunning” the bolus. The bold horizontal lines show one example of a multi-step quantized timing algorithm for beginning the lower station acquisition based only on knowing the AC-F time (deduced from the initial time-resolved lower station run). The % venous enhancement expected based on this database (assuming use of sub-systolic thigh BP cuffs) is shown for each proposed timing interval. Conclusion Using only the AC-F time derived from a time resolved lower extremity dataset, time delay algorithms for time between upper and lower station acquisition (i.e. table propagation speed) can be generated. One such example quantized into 4 discrete ranges is shown, and will never outrun the bolus. In this example, our 112 extremity database predicts no venous when AC-F time is >50s, and <15% venous when AC-F time is <50s. This and other algorithms are being clinically investigated, and data from their use will be presented. References (1) Maki et al. Maximizing SNR for Peripheral MRA Using a priori Knowledge of Bolus Kinetics and the Optimal Choice of Imaging Parameters. MRA Club Istanbul, 2007.


5.8 Highly Accelerated Contrast-Enhanced MRA: Benefit of Complex Subtraction

Ioannis Koktzoglou1, John J. Sheehan1, Eugene E. Dunkle1, Wei Li1, Felix A. Breuer2, Robert R. Edelman1

1Department of Radiology, NorthShore University HealthSystem, Evanston, IL USA 2Research Center Magnetic Resonance Bavaria, Würzburg, Germany

Purpose: The purpose of this study was to identify performance differences between complex subtraction and magnitude subtraction in the setting of highly-accelerated contrast-enhanced (CE) MRA. Methods: Imaging was performed on a 32-channel 3.0 Tesla MR scanner (MAGNETOM Verio, Siemens Healthcare, Erlangen). A vascular phantom study was performed to examine the effects of complex and magnitude data subtraction on parallel imaging reconstruction quality over a wide range of acceleration factors. The vascular phantom consisted of intravenous extension tubing that was imaged twice with a FLASH acquisition when containing 0.125 mM (T1 ≈ 1400 ms) and 31.25 mM (T1 < 50 ms) gadopentetate dimeglumine (Gd-DTPA) (Magnevist®, Bayer Healthcare, Berlin). Raw data were reconstructed using simulated GRAPPA reduction factors (R) ranging from 2 to 12 (net acceleration factors (AF) of 1.86-6.53). Images were obtained by subtracting reconstructed magnitude images or k-space data prior to the GRAPPA reconstruction. The root mean square error for each subtraction scheme was computed with respect to non-accelerated, fully sampled reconstructions. Human volunteers (n = 7) were imaged with time-resolved CE-MRA acquisitions (TWIST) to verify the relevance of the results from the phantom study. Volunteers underwent two TWIST scans separated by 31.0 ± 0.9 min (10 cc injection of 0.5 M Gd-DTPA at 3 cc/s; 15 mL saline chaser). The first acquisition was acquired using a large reduction factor of 8 (AF = 4.33); the second acquisition was performed using R = 2 (AF = 1.77). Data were reconstructed using complex and magnitude subtraction and geometry factors were calculated using the methodology of Breuer et al. [1]. Results: RRMSE values obtained in the phantom study increased with AF (Figure 1). For net acceleration factors less than or equal to the number of unique receiver coil positions along the phase-encoding direction (AF ≤ 3), RRMSE values were small and similar for magnitude and complex subtraction schemes. Substantial increase in RRMSE was observed with both subtraction schemes at AF > 3. In this regime, the rate of increase in RRMSE with magnitude subtraction was more than twice that measured with complex subtraction. Figure 2 shows images obtained in volunteers at net acceleration factors of 1.77 and 4.33. Magnitude and complex subtraction provided similar image quality at AF = 1.77, however, better image quality was obtained with complex subtraction at AF = 4.33, chiefly in the form of reduced background noise and improved vessel conspicuity. Median and mean geometry factors were significantly larger with magnitude subtraction processing than with complex subtraction processing at both acceleration factors (P < 0.05).

Figure 1. Dependence of relative root mean square error (RRMSE) on the net acceleration factor obtained with magnitude and complex subtraction.

Figure 2. Time resolved CE-MRA images of the calf obtained with magnitude and complex subtraction. Similar image quality was obtained at the low AF of 1.77 (R = 2). Complex subtraction reduced noise amplification and provided better image quality at the large AF of 4.33 (R = 8).

Conclusion: CE-MRA using complex subtraction processing prior to GRAPPA reconstruction reduces noise amplification related to the geometry factor and supports the use of large acceleration factors better than CE-MRA based on magnitude subtraction. The benefits of CE-MRA performed using complex relative to magnitude subtraction increase with larger parallel imaging acceleration factors. References: [1] Breuer et al. Magn Reson Med 2009; 62(3):739-746.


5.9 Comparison of CAPR MRA with CT Angiography for Evaluation of Below the Knee Runoff:Preliminary Results

Phillip M. Young MD, James F. Glockner MD, PhD, Terri J. Vrtiska MD, Thanila Macedo MD, Clifton R. Haider PhD, Petrice M. Mostardi BS, Stephen J. Riederer PhD.

Department of Diagnostic Radiology, Mayo Clinic, Rochester, MN, USA Purpose: To compare radiologist confidence in CTA and CAPR MRA in a cohort of clinical patients. Methods and Materials: Our study was HIPAA and IRB-compliant, and all subjects signed informed consent prior to enrollment. 14 consecutive subjects were imaged for clinical indications with CTA and CAPR MRA. CTA technique: 64-detector row scanner with injection of 145 mL Omnipaque 350, 25 mL at 5 ml/sec and 120 ml at 4 ml /sec and 30 ml of saline at 4 ml/sec. The CT examination covered from 4 cm above the iliac crest to the bottom of the feet. Parameters included 0.5 sec rotation time, pitch 0.8, 15 mm/rotation, 120 kVp, 250 mAs. Automated triggering and exposure control were employed. CT spatial resolution was 0.6 x 0.6 x 2.0 mm3. CAPR MRA protocol followed a previously described technique (2): 0.2 mmol/kg gadobenate dimeglumine injected at 3ml/sec followed by 20 ml saline at 2ml/sec. Imaging was on a 3T scanner, 8 channel receive array coil, 3D GRE Sequence, TR/TE = 5.85/2.7 ms, FA 30°, BW = ±62.5 KHz, 40 (S/I) x 32 (L/R) x 13.2 (A/P) cm3, 8x SENSE acceleration, spatial resolution 1 mm3, frame time 4.9s, temporal footprint 17s. Some patients were referred for CAPR MRA because of nondiagnostic CTA. 2 board-certified radiologists assessed 5 vessels in each leg, divided into 11 segments, on both CT and MR in blinded and randomized fashion according to criteria in Table 1. Reader 1 was more experienced in CTA, and reader 2 was more experienced in MRA. Results: On CTA, Reader 1 characterized 57 segments as unassessable, and 23 segments as having moderate uncertainty. On CAPR, however, reader 1 characterized only 1 segment as unassessable and 12 segments as having moderate uncertainty. Reader 2 characterized 35 segments as unassessable on CTA, and 40 segments as having moderate uncertainty. On CAPR, reader 2 characterized only 1 segment as unassessable and 11 segments as having moderate uncertainty. Average reader confidence on CTA was 1.39 +/- 0.75 for reader 1 and 1.37 +/- 0.68 for reader 2. On MRA, average confidence was 1.05 +/- 0.22 for reader 1 and 1.05 +/- 0.22 for reader 2. In 55/308 segments imaged on CT (18%), calcification limited vessel evaluation. In these segments, the average diagnostic confidence ranking was 1.88+/- 0.60 on CTA, and 1.07 +/- 0.26 on MRA. In no case did ASSET artifact on CAPR MRA limit clinical interpretation. Discussion: Although our sample size is small and there is some referral bias because some of our subjects were recruited because of poor evaluation on CTA before CAPR MRA was performed, our results indicate that CAPR MRA can overcome some limitations of CTA and result in improved diagnostic confidence for evaluating lower extremity arteries, because of time-resolved data acquisition, excellent spatial resolution, and lack of inhibition by calcification. The major limitation to vessel evaluation in CAPR MRA in these subjects was loss of signal toward the edge of the coil. Currently, limited anatomic coverage is the greatest limitation of CAPR MRA compared to CTA for imaging the lower extremities; current work in coil design and multi-station runoff imaging may help make this a first-line diagnostic test for evaluation of lower extremity runoff vessels, particularly in patients with known or suspected calcification or abnormal or asymmetric inflow patterns. Figure 1: a. CTA MIP with bones removed demonstrates poor arterial opacification and venous contamination. b. Best arterial phase MIP image from CAPR MRA demonstrates clear vessel opacification. References: 1. Haider CR et al. Magn Reson Med 2008;60(3):749–760. 2. Haider et al. Radiology. 2009;253(3):831-843.

Table 1: Vessel Status 0 Normal or stenosis <50% 1 Stenosis >50% 2 Occlusion Confidence 1 Full diagnostic confidence 2 Moderate uncertainty 3 Cannot be ascertained MRA: Sense or other artifact? 0 None

1 Visible but does not affect diagnostic utility

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6.1 XIP Software Suite for XFM (X-Ray Fused with MRI) Emre Özdal 1, Abdülkadir Yazıcı1, Cengizhan Öztürk 1

1 Biomedical Engineering Institute, Boğaziçi University, Istanbul, Turkey Objective X-Ray Fluoroscopy (XF) is one of the most commonly used imaging techniques in interventional radiology, with the main disadvantage of low soft tissue contrast. XFM tries to overcome this using information from MRI. In XFM, anatomical details gathered from a priori MRI is overlaid on top of live XF images during interventions. To achieve this, registration between MRI and XF spaces should be done, for which markers visible both in MRI and XF could be used. Considering all the requirements of the final project goal, which is a comprehensive XFM software for early clinical research, Extensible Imaging Platform (XIP) is chosen for its development environment. XIP is supported by groups like caBIG and Siemens Corporate Research. Methods During the intervention, additional soft tissue information (For instance: In endovascular cardiac interventions, detailed anatomical positions of the segments of heart) would have vital importance to decrease the risk of mistakes and for the ease of guidance of the surgeon. There are fusion methods that combine several imaging modalities to support interventions with additional functional or anatomical information.

In our project main goal is to overcome the lack of soft tissue contrast resulting from working principles of XF. To achieve this goal, fusion of soft tissue data gathered from another imaging modality on XF image in real time is used. To gather the soft tissue data in our project Magnetic Resonance Imaging is selected as the second imaging modality because of high soft tissue contrast. To combine two imaging modalities (XF and MRI) in an X-Ray Fused MRI (XFM) project there is a procedure to be followed. The steps of the procedure are stated as below:

• First the subject is equipped with a belt containing a series of fiducial markers that can be identified in both modalities.

• A marker localization MRI scan is done with optimum parameters set for marker contrast

• Another MRI scan is done for detailed soft tissue information in the region of interest (ROI)

• Subject is taken to XF device, and a series of images of the ROI are taken with different primary angle values ranging from – 30 to +30

• All the images taken under MRI and XF are transferred to XFM suite to make the registration between two spaces of modalities

• During the intervention fused soft tissue data over XF image is formed with registration data calculated in the previous steps.

XIP (extensible imaging platform) is an open source software platform, which is developed for prototyping medical software and image processing tools rapidly in research areas. Today, usage of post-processing of medical images and image processing algorithms are increasing in medical operations. XIP is developed by caBIG. Results Specified modules of XFM project are being implemented in XIP. Performance tests of developed modules and demonstrations showed that XIP is suitable for our project. Hardware related tests of our project are done in National Instutes of Health (NIH Bethesda, ABD) and UMRAM (Bilkent University).


6.2 Multi-baseline PRF-based Thermometry for MR-guided Interventions using an Extensible Real-Time Platform

Peng Wang and Orhan Unal Medical Physics and Radiology, University of Wisconsin, Madison, WI, USA

PURPOSE: To investigate the effectiveness of multi-baseline PRF-base MR thermometry to eliminate artifacts caused by motion implemented on RTHawk, extensible software architecture for real-time MR acquisition and reconstruction platform. METHODS: RTHawk is a software architecture that permits a variety of pulse sequences, acquisition trajectories, and reconstruction techniques to be easily developed and interleaved at run-time on GE scanners [1]. Real-time MR temperature mapping was implemented using a 2D fast gradient-echo spiral technique using the RTHawk platform (HeartVista, CA). A multi-baseline strategy was used to correct the motion-induced artifacts in the temperature maps induced by tissue motion. Before RF ablation treatment, N consecutive reconstructed complex images were stored in a lookup table [2]. During hyperthermia, arriving images were matched to the images in the table using the maximum correlation coefficient. To assess the robustness of the method, a motion was induced by the built-in rocker capability of the MR scanner table (5 mm distance, speed = 10 mm/s). A 6F catheter with a tip tracking coil and bipolar RF ablation tip was built and used for ex-vivo ablation of excised bovine liver tissue. Tissue temperature was also measured with fiberoptic temperature probes (Neoptix, Quebec, Canada). RESULTS AND DISCUSSION: Starting at 18 °C, the tissue was slowly heated up to

53 °C in about 7 minutes according to the temperature probe placed near the tip of the catheter. N = 45 was chosen as the number of baselines images obtained before heating. The evolution of temperature at the vicinity of catheter tip is shown in Figure 2. The temperature obtained in a small ROI near the catheter tip shows good agreement with the fiberoptic sensor measurement near the catheter. Figure 1. Comparison of temperature evolution obtained with MR thermometry and fiberoptic temperature probe near the RF ablation tip.

CONCLUSIONS: Initial results suggest indicate that PRF-based MR thermometry is suitable for monitoring temperature changes during MRI-guided RF ablation. The multi-baseline method works well to overcome the artifacts induced by tissue motion. RtHawk abstracts away much of the complexity of pulse sequence and reconstruction programming, therefore simplifying development. REFERENCES: [1] Santos et al. Proc IEEE Eng Med Biol Soc. 2:1048, 2004 [2] Rieke et al., JMRI 27:376, 2008

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6.3 Fat-Suppressed Steady State Imaging for Non-Contrast Enhanced MR Angiography in the Thorax & Abdomen

Jessica Klaers, Kevin Johnson, Ethan Brodsky, Eric Bultman, Chris François, Scott Reeder, Walter Block

Depts of Medical Physics, Biomedical Engineering, Radiology, University of Wisconsin, Madison, USA

INTRODUCTION Several variations of the balanced steady state free precession (bSSFP) acquisition have been proposed to provide non-contrast enhanced MR angiograms (NCE MRA) without the injection of a contrast bolus due to the preferably bright fluid signal [1-4]. However, these sequences are sensitive to banding artifacts and unwanted bright lipid signal. We have previously achieved successful results with a 3D radial Linear Combination SSFP (LC-SSFP) sequence used in conjunction with a real-time adaptive expiratory respiratory gating method for high resolution fat/water separated renal NCE MRA [5-6]. Here we present the initial results of this method extended for application in the thorax without the use of ECG gating. Additional preliminary results using a newly developed 3D radial fat-suppressed Alternating TR (FS-ATR) SSFP method are compared relative to our previous work for renal NCE MRA. METHODS Placement of the stopband in the 3D radial LC-SSFP technique requires setting the center frequency at the midpoint of fat and water before sampling k-space twice with the RF phase alternating by π radians each TR in the first pass and remaining constant in the second pass. Linear combinations of these two passes yield water and fat volume images [7]. Alternatively, our 3D radial implementation of the fat-suppressed ATR SSFP method [8-9] only requires a single k-space acquisition while providing comparable fat-suppression. This technique employs two different alternating length TRs with a TR2:TR1 ratio of 1:3 and RF phase cycling to shape the spectral frequency response to create a broad stopband over the fat resonance. For implementation at 1.5T, TR1 and TR2 were chosen to be 3.45 ms and 1.15 ms, respectively, with the phase of the second RF pulse set to 90°. A novel real-time adaptive expiratory respiratory gating method was implemented based on a respiratory bellows reading for each of the above-described methods [6]. All imaging was performed on a 1.5T clinical scanner (HDx, GE Healthcare, Waukesha, WI). The cardiac MR angiograms were acquired on 2 patients without the use of contrast agents or ECG gating. Additional preliminary MR angiograms of the renal arteries were acquired on a volunteer without the use of contrast agents. The mean scan time was 6:15 min, with a consistent 3:20 min of data collection. RESULTS & DISCUSSION Preliminary cardiac MRA results using the LC-SSFP method are promising with impressive visualization of both the ascending aorta and vascular walls without the use of ECG gating (Fig 1). Furthermore, excellent depiction of the renal arteries has been demonstrated without the use of contrast agent for each of the LC-SSFP and FS-ATR SSFP methods (Fig 2). Relative to other non-contrast enhanced methods, the major advantages of these approaches are the inherent robustness to motion and the suppression of fat signal, particularly in larger patients where adiposity leads to a reduction in image quality using other methods. The FS-ATR method demonstrates comparable performance relative to LC-SSFP at 1.5T and will offer a substantial advantage when implemented for NCE MRA at 3.0T, as it avoids the redundant sampling typical of LC-SSFP while maintaining a short TR of similar duration. REFERENCES 1) Maki et al. AJR 188:540-546. 2) Katoh et al. Kidney International 66:1272-78. 3) Herborn et al. Radiology 239(1):263-268. 4) Wyttenbach et al. Radiology 245(1):186-195. 5) Klaers et al. ISMRM 2008, 2906. 6) Johnson et al. ISMRM Motion Correction Workshop 2010. 7) Vasanawala et al. MRM 43:82-90. 8) Leupold et al. MRM 55(3):557-565. 9) Klaers et al. ISMRM 2010, 233.

FIGURE 1 Representative targeted MIP images. Preliminary axial (A), sagittal (B), and coronal (C) images depicting the thoracic vasculature and heart wall using the LC-SSFP technique without ECG gating. Note the clear depiction of the ascending aorta (C).

FIGURE 2 Oblique thick-slab MIPs of the renal arteries as acquired with LC-SSFP (A,C) and FS-ATR (B,D). Note the reduction of the static fluid and venous signal in the FS-ATR images relative to LC-SSFP.


7.1 Unlocked Motion in Turbo Spin Echo of the Cervical Carotid Artery

Dennis L. Parker, PhD, Jason Mendes, MS, Jordan Hulet, Scott McNally, MD, Seong-Eun Kim, PhD, John Roberts, PhD, and Jerry Treiman, MD

There is much evidence that the nature of the plaque and not the degree of stenosis is

responsible for TIA and stroke (1). Emboli that cause TIA and stroke may consist of atheromatous debris, platelet aggregates or thrombus and may occur at the time of plaque rupture, plaque degeneration, or platelet aggregation. Plaques with irregular surface characteristics are a nidus for platelet aggregation, atheromatous fragmentation, and subsequent embolization (1) and indicate an increased risk of ipsilateral ischemic stroke. Other risk factors for ipsilateral stroke include the presence of intra-plaque hemorrhage, severe flow disturbances around the encroaching lesion, plaque cap thinning (2), ulceration, abnormal plaque motion (3-6), thrombotic activity (7), and inflammation (8).

For nearly 20 years we in the MRA community have been developing MRI and MRA techniques to visualize disease in the carotid arteries. White-blood time of flight (TOF) techniques have been augmented by turbo-spin-echo (TSE) black-blood techniques. With double inversion recovery (DIR) for additional blood suppression, TSE offers proton density weighted (PDw), T1w, and T2w contrasts to help depict the internal structure of the atherosclerotic plaque. However, TSE carotid imaging sequences are subject to artifacts due to motion of the carotid wall with cardiac pulsations, breathing, and swallowing. Such motions cause blurring and ghosting artifacts that can severely degrade image quality. In all our research to improve MRI techniques to image the cervical carotid arteries, we have continuously found artifacts due to motion to be one of the primary causes of procedure failure. Further, residual blood signal is often difficult to discriminate from complex plaque structure.

In this presentation we analyze the information added when the conventional 2DTSE when ECG correlation is combined with temporally constrained multiple-coil reconstruction to become dynamic 2DcineTSE. The details of the technique are presented at this meeting by Jason Mendes, who created the implementation and demonstrated the feasibility. In brief, when multiple RF coils are used and with two or more averages, it is possible to add a temporal constraint to reconstruct a sequence of ECG correlated images. The net result is that the conventional 2DTSE image that is reconstructed from the entire dataset is transformed into a movie of the beating heart, and it is clear that the conventional image is some average of the dynamic structures in the neck. Conversion from this conventional image to the movie sequence demonstrate the dynamic properties of the neck, including expansion and contraction of the arterial wall with the pressure pulse, opening and closing of vein valves, the cyclic property of complex blood flow that causes the residual blood signal in the conventional TSE image, and even pulsation of the spinal CSF fluid.

Our very preliminary evidence is that cineTSE will enhance the ability to sort out the structure of complex arterial plaque. The value in the evaluation of the cervical carotid artery seems evident. It is likely that this technique will be of use in a variety of other vascular beds, including the heart itself, as well as in a variety of other applications. 1. Moore WS, Hall AD. Importance of emboli from carotid bifurcation in pathogenesis of cerebral ischemic attacks. Arch Surg 1970;101(6):708-711 passim. 2. Dhume AS, Soundararajan K, Hunter WJ, 3rd, Agrawal DK. Comparison of vascular smooth muscle cell apoptosis and fibrous cap morphology in symptomatic and asymptomatic carotid artery disease. Ann Vasc Surg 2003;17(1):1-8. 3. Hennerici MG. The unstable plaque. Cerebrovasc Dis 2004;17 Suppl 3:17-22. 4. Gortler M, Goldmann A, Mohr W, Widder B. Tissue characterisation of atherosclerotic carotid plaques by MRI. Neuroradiology 1995;37(8):631-635. 5. Lovett JK, Gallagher PJ, Hands LJ, Walton J, Rothwell PM. Histological correlates of carotid plaque surface morphology on lumen contrast imaging. Circulation 2004;110(15):2190-2197. 6. Molloy J, Markus HS. Asymptomatic embolization predicts stroke and TIA risk in patients with carotid artery stenosis. Stroke 1999;30(7):1440-1443. 7. Spagnoli LG, Mauriello A, Sangiorgi G, Fratoni S, Bonanno E, Schwartz RS, Piepgras DG, Pistolese R, Ippoliti A, Holmes DR, Jr. Extracranial thrombotically active carotid plaque as a risk factor for ischemic stroke. Jama 2004;292(15):1845-1852. 8. Fleiner M, Kummer M, Mirlacher M, Sauter G, Cathomas G, Krapf R, Biedermann BC. Arterial neovascularization and inflammation in vulnerable patients: early and late signs of symptomatic atherosclerosis. Circulation 2004;110(18):2843-2850.


7.2 Phantom study of Black Blood CUBE with Flow-Sat-Prep Mitsuharu Miyoshi, Naoyuki Takei, Hiroyuki Kabasawa

MR Applied Science Laboratory Japan, GE Healthcare Japan

Purpose Black Blood imaging is an important application of MR Angiography. Several flow saturation methods were already reported. Variable flip refocusing CPMG (CUBE [1]) is a flow saturation data acquisition. Diffusion preparation [2] (MSDE [3] or Flow-Sat-Prep (FSP) [4]) is a Velocity Encoding (VENC) based preparation pulse. In this study, CUBE and FSP are combined and the flow phantom saturation was measured with short TE, large crusher and slow VENC. Methods Pulse sequence is in Fig.1. Single refocus pulse was used for FSP. In CUBE, several echoes were skipped before 3D data acquisition. Short TE is a key for T1 or PD contrast imaging because T2 decay occurs in both FSP and skipped echoes. TE in this study was defined as the sum of FSP T2 decay time and effective TE of CUBE. Flow signal was measured in the following condition. The velocity of water flow phantom at the center of the tube was around 50 mm/s, which was measured with 2D Phase Contrast. (1) The read gradient crusher area (orange in Fig.1) was changed between 1.69 and 23.49

s*T/m (1/ /1mm), and the number of skipped echoes were changed between 0 and 12. 　　FSP was not used. (2) VENC of FSP (green in Fig.1) was changed between 12.5 and 100 mm/s with 1.69 crusher and two skipped echoes. (3) FSP and large crusher were combined with optimized VENC and skipped echoes and images were compared. Results Fig.4-a is the Flow phantom image. Although flow signal was saturated at the center of the tube, it was high at the edge because of slow flow (red square). The edge signal was used as flow signal. (1) Result is Fig.2. Large crusher reduced edge signal. On the other hand, longer skipped echoes slightly reduced edge signal. (2) Result is in Fig.3. 50 mm/s VENC was enough to reduce edge signal and it corresponded to the flow velocity of the phantom. (3) Fig.4 shows the effect of crusher and FSP. Residual flow signal was depicted at the different location in 23.49 crusher (Fig.4-b) and FSP (Fig.4-c) images. In FSP and large crusher combined image (Fig.4-d), flow signal was saturated at the center and edge of the tube. Discussions Although 12.5 mm/s VENC reduces edge signal more, eddy current of VENC gradient might be increased and banding artifact occurred on the image. Slower VENC increases T2 decay time, too. In combined case (Fig. 4-d), TE was 19.4 ms and extension of TE was controlled. Combination of large crusher CUBE and slow VENC FSP resulted in the best flow saturation in this study. References [1] Busse R. et al., MRM 51:1031 (2004) [2] Koktzoglou I. et al., JMRI 25: 815 (2007) [3] Wang J. et al., MRM 58:973 (2007) [4] Miyoshi M. et al.,Proc ISMRM 15: 180 (2007)

Fig.2: Crusher area, skipped echoes and signal intensity

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7.3 Acceleration-sensitive MRI: Analysis of Complex Vascular Flow Patterns

Alex J Barker1, Felix Staehle1, Simon Bauer1, Bernd Jung1, Michael Markl1 1University Hospital Freiburg, Department of Radiology, Medical Physics

Purpose: Local and bulk blood acceleration provides valuable functional information regarding vessel compliance, intravascular pressure gradients, and local flow derangement. With this in mind, investigators have employed phase-contrast magnetic resonance imaging (PC-MRI) to measure blood velocity and subsequently the acceleration field through the application of a spatio-temporal derivative. Although this derivative technique provides an estimate of the acceleration field, the direct measurement of acceleration may be advantageous due to error-propagation and velocity noise amplification when calculating a derivative parameter. [1-3] In this abstract, we present a gradient optimized acceleration sensitive sequence developed to reduce Te and therefore permit 3-directional, volumetric scans to be feasibly implemented in volunteers. [4] Methods: 6 volunteer measurements (at the left ventricular outflow tract) were performed at 1.5T (n=3,Avanto) and 3T (n=3,Trio). 3 acceleration-encoded PC-MRI sequences were implemented with sensitivities of ±50 m/s², ±100 m/s² and ±150 m/s². Gradient optimization and sequential acceleration encoding [4] resulted in comparatively short TE/TRs of 7.0-7.3/9.5-10ms, 5.9-6.2/8.3-8.8ms and 5.4-5.7/7.8-8.2ms and temporal resolutions of 19-20 ms, 16.6-17.6ms and 15.6-16.4ms. PC-MRI velocity data were acquired with TE= 2.6-2.8ms and temporal resolutions of 19.2-20.8 and 37.2-39ms. The acceleration-encoded data was compared to the velocity-derived acceleration using two regions of interest proximal and distal to the aortic valve plane (Fig. 1a). Results & Discussion: Fig 1 summarizes the major findings of this work. The noisy nature of the vector magnitude maps obtained from the velocity-derived acceleration (Fig 1c) is apparent when compared to the directly-measured acceleration (Fig 1d). The acceleration vector magnitude for both measurement methods was quantified in the regions of interest (ROI’s) shown in Fig 1a and plotted in Fig1f-g. These graphs demonstrate agreement between the velocity-derived and directly measured acceleration as well as the lower standard deviation of the acceleration in the directly measured data (as shown by the error bars). Of particular interest is the signal loss caused by intravoxel dephasing, which clearly correspond to regions of high acceleration such as in the case of vortex formation (shown by the arrows, Fig 1b,e). This signal loss in the acceleration-encoded magnitude images may provide a mechanism to visualize complex flow events quicker than the lengthy postprocessing of phase images.

Fig 1. (a) Intensity magnitude images from velocity- & (b) acceleration-encode sequences; (c) acceleration vector magnitude maps derived from the velocity- & (d) acceleration-encode sequence; (e) velocity field overlaid on the acceleration intensity image from ‘b’; (f-g) Average acceleration measured in ROI’s 1&2 (shown in ‘a’) – error bars indicate standard deviation; (h) Intravoxel dephasing width over the cardiac cycle – measurement position shown by arrows in ‘b’.

References:[1] Tasu, JP, et al., 1997, Magnet Reson Med, Vol. 38, pp. 110-6. [2] Tasu, JP, et al., 2000, Magnet Reson Med, Vol. 44, pp. 66-72. [3] Balleux-Buyens, F, et al., 2006, Phys. Med. Biol., Vol. 51, pp. 4747-58. [4] Staehle, F, et al., 2009,Proc. of the ISMRM, Abstract #2665.


7.4 Multivariate Measurement of Trans-stenotic Pressure Gradient

Nahee Lee1,2, Sejin Heo1, Suyoung Yoon1, Junghun Kim1, Younghae Do2, Chelwoo Park3, Jongmin Lee, MD. Ph.D.1,4

1Department of Biomedical Engineering, 2Mathematics, 3Mechanical Engineering, and 4Radiology, Kyungpook National University, Daegu, Korea

Purpose Pressure gradient offers significant information about loss of hemodynamical energy

through vascular stenosis. Nevertheless, it is difficult to measure trans-stenotic pressure gradient non-invasively. The simplified Bernoulli equation is mainly used for non-invasive measurement of pressure gradient in spite of its unrealistic limitations. The aim of this study is to establish a multivariate measurement technique for trans-stenotic pressure gradient. Materials and Methods An adjustable stenotic flow model was produced using variable length (1-7Cm) and

degree (10-70% in Area) of stenotic segments. The non-stenotic segment of rigid tube had 1.9 Cm in diameter with luminal flow of Newtonian fluid at the speed of 110 to 140 Cm/sec. Trans-stenotic pressure gradient was measured physically using real-time manometer and used as reference standard. The input variables comprised of pre-stenotic flow velocity, degree and length of the stenosis. Based on fitting equations between each input variable and reference standard value, multivariate formula for pressure gradient measurement was induced. Subsequently, the same flow model was scanned using velocity-encoded phase contrast

imaging under 3T MRI. Pre-stenotic flow velocity was measured using commercially available MR velocimetry program. The correlation was analyzed between simultaneously and physically measured pressure gradient values and calculated values using our formula and conservative method, simplified Bernoulli equation. Results In linear correlation analysis, simplified Bernoulli method and our method revealed R2 values of 0.88 versus 0.99 based on physically measured pressure gradient. In paired t-test, our method showed statistical significance in contrast to statistically insignificant simplified Bernoulli method. Conclusion Self-developed multivariate technique could measure trans-stenotic pressure gradient reliably and was better than conservative method using simplified Bernoulli method.


7.5 Quantitative Susceptibility Mapping of Intracerebral Hemorrhage

Tian Liu1, Deqi Cui2, Liuquan Cheng3, Min Lou4, Jianzhong Zhang4, Minming Zhang4, Yi Wang1,2

●1, 2 Biomedical Engineering & Radiology, Weill Cornell Medical College ●3 Radiology, 301 Hospital ●4 Radiology, 2nd affiliated hospital of Zhejiang University

Purpose: Gradient Echo MRI (GRE) is a method of choice for detecting intracerebral hemorrhage (ICH) due to its sensitivity to blood breakdown products with substantial paramagnetic susceptibility. However, the hypointensity of ICH in a GRE image is highly dependent on echo time TE and may be confounded with calcifications, prohibiting reliable image comparison or assessment of disease progression (1). In this study, we propose to use a novel technique quantitative susceptibility mapping (QSM) as an objective measurement of ICH. A comparison with T2* weighted image (T2*w), susceptibility weighted image (SWI) and R2* map showed QSM has the least dependence on the range of echo time used. Methods: In QSM, both the magnitude and phase images of a multiecho GRE acquisition are utilized to calculate the susceptibility(2). Because susceptibility is an intrinsic tissue property, it is independent of imaging parameters. Furthermore, the diamagnetism of calcification allows for a clear distinction from hemorrhages. Patients with cerebral hemorrhage were imaged on a 3T MR Scanner using an 8 channel birdcage head coil and a multiecho spoiled gradient echo sequence with 10 TEs; uniform TE spacing = 5.2 ms and TR = 68 ms. T2*w and SWI were reconstructed at different TEs. R2* and QSM were reconstructed using the first N echoes, where N was varied between 2 and 10. Volumes of the hemorrhage on T2* and SWI, total R2*, and total susceptibility in the hemorrhage were measured to gauge their dependence on the range of used TEs. Results: Patients with microbleeds and hemorrhage are shown in Figs.1&2. The appearance of the QSM and susceptibility values were independent of the range of TEs used, in sharp contrast with the sensitive TE range dependence of hypointensity in T2*w and SWI. In addition, the foci of negative susceptibility in the atria of the lateral ventricles (green arrows in Fig. 1) were interpreted as calcification, whose diamagnetism has been confirmed experimentally(3). Conclusion: In this study, we performed T2*w, SWI, R2* and QSM reconstructions on ICH patients to gauge the influence of TE on the images. QSM mapped ICH with appearance and value invariant with echoes, providing a standardized measure of hemorrhage in GRE MRI. References:1.S. M. Greenberg et al., Lancet Neurol 8, 165 (Feb, 2009). 2. J. Liu et al., in ISMRM(2010), pp. 4996. 3. L. de Rochefort et al., Magn Reson Med 60, 1003 (Oct, 2008).

Fig. 1. QSM provides a more objective evaluation of the hypointense foci on the magnitude images.

Fig. 2. A comparison with T2*w, SWI and R2* map showed QSM has the least dependence on TE


7.6 Developing Guidelines for Successfully Interleaving Active Tracking of Catheters with Steady-state Imaging

Sequences B. Grabow1, E.K. Brodsky 2, O Unal 1, W.F. Block 1-3

Departments of Medical Physics1, Radiology2, and Biomedical Engineering3, University of Wisconsin-Madison, Madison, WI, USA

Objective Tracking of catheters during MR guided procedures is accomplished by using previously acquired roadmap images, solely tracking the catheter during catheter manipulation, and reacquiring roadmap images when necessary. Active catheter tracking [1], while holding the promise of locating a catheter at several frames per second while continuously imaging, is complicated by the periodic interruption of imaging sequences which degrades image quality. We investigate the influence of imaging and tracking sequences on image quality and develop a set of guidelines to minimize degradation by minimizing disturbances in the steady-state. Materials and Methods We hypothesize if the imaging sequence can share information with the tracking sequence on matters such as RF phase cycling and gradient spoiling, the tracking sequence may be able to minimize disturbances to the imaging sequence. In this work, the central focus was not actually to track a catheter, but to appreciate how differences between the tracking and imaging pulse sequences caused possible image degradation.To investigate how differences between imaging and tracking pulse sequences can affect the imaging steady-state, a flexible pulse sequence program with interleaved imaging and tracking sequences was developed on a GE Healthcare Signa 1.5T system (Waukesha, WI). The supported imaging sequence included RF-spoiled T1-weighted imaging, coherent gradient echo imaging (GRASS) and fully refocused steady-state imaging. The tracking sequence was designed similarly to operate in a similar range of gradient-recalled configurations. First, the consequences of differences between RF phase cycling during imaging and tracking was investigated. Next, experiments studying the impact of differences in flip angle, TR, and gradient spoiling axis are described. Results Imaging sequences which depend primarily on the longitudinal steady-state were found to be more robust to interruptions than sequences that depend on the transverse steady-state. Interleaving of active tracking and the coherent gradient echo sequence GRASS in humans demonstrates dramatic changes in image contrast at high flip angles (60 degrees). In Fig. 1b, maintaining all RF parameters and gradient spoiling parameters during tracking as during imaging caused little change relative to the ref. image in Fig. 1a. Though not practical for tracking, using the same slice thickness for tracking maintains the positive signal within the ventricles and all vascular in-flow. However, using a more practical tracking RF pulse which excites the entire head in Figure 1c destroys the signal coherence pathways which provide positive cerebrospinal fluid (CSF) signal.

Figure 1 a) Reference GRASS axial image without tracking interruption. b) Tracking sequence maintains all imaging parameters, including thin excitation slice profile. c) Widening the tracking excitation removes CSF/brain contrast.

Conclusion An investigational pulse sequence to mimic an interleaved imaging and active catheter tracking applications was developed to study how periodic interruptions for active tracking can disturb the imaging steady-state. Efforts to have the tracking sequence mimic the imaging sequence flip angle, TR, and RF phase cycling scheme result in higher image quality. References 1) Dumoulin CL et al MRM 1993; 29(3) 411-415


7.7 An automated approach to vessel lumen analysis – Vessel Explorer

Liesbeth Geerts, Javier Olivan Bescos, Jeroen Sonnemans, Raymond Habets, Joost Peters

Philips Healthcare, Best, The Netherlands Purpose Therapeutic decisions in patients with carotid artery stenosis (CAS) are based on maximal internal carotid artery (ICA) stenosis. The treatment criteria are based on specific linear measurements comparing the residual diameter of the lumen with that of the normal carotid beyond the bulb (NASCET criteria). Tools to measure the degree of stenosis are often considered as cumbersome, complex or requiring too much interaction. This is why routine measurements such as stenosis degree, stenosis length, or vessel diameter are usually done by using “eyeballing”, i.e. assessment with the unaided eye of the expert. However, a subjective rating of carotid stenosis may lead to erroneous estimation of the severity of disease [1]. It was our purpose to develop a fast and simple method for stenosis measurements, that could be performed in virtually the same time as eyeballing, with minimal inter- and intra-user variability. Methods To minimize processing time and to avoid inter- and intra user variability, an analysis tool was required that largely eliminates manual interaction: A pathless tracker – VesselExplorer– was developed that features automatic optimal MPR alignment, automatic window width/level settings, automatic lumen contour delineation and semiautomatic vessel centerline computation. Measurements Stenosis measurements were performed in a phantom of the carotid bifurcation with 50% stenosis in the internal carotid artery using a conventional 3D-FFE MRA protocol. Four clinical application experts estimated the stenosis degree manually by drawing contours in cross sections at the stenotic and reference locations respectively. The stenosis error is defined relative to the stenosis of the phantom. The time needed to assess the stenosis was recorded. Results The error in the stenosis measurement of the manual delineation was -6.8% ± 10.5%. The automatic method using VesselExplorer yielded significantly better results with an error of -1.5% ±0.94%. Average processing time to assess stenosis manually (select window width/level, aligning views, drawing 2D measurements on the cross section) was 6 minutes. With VesselExplorer it was less than 10 seconds. Conclusion VesselExplorer provides radiologists with robust quantitative measurements of vessels in a quick, simple, and intuitive way. The tool requires minimal interaction while efficiently providing the frequently required measurements. [1] Pelz et al. Can Assoc Radiol J. 1993 Aug;44(4):247-52.


7.8 Potentials of ultra high field strength 7T MRA: Comparison with other imaging modalities

Chang-Ki Kang, Young-Bo Kim, Zang-Hee Cho Neuroscience Research Institute, Gachon University of Medicine and Science,

Korea PURPOSE: Ultra-high-field 7T MRI has provided the potentials of anatomical and functional applications in human in vivo 1-2. However, 7T MRI for vascular imaging, that is, 7T MRA, has fallen behind comparatively, but some groups including ours began to shed light on 7T MRA, providing for several astonishing vascular images 3-4. In this study, we would like to assert the advantages of 7T MRA for microvascular imaging, especially for diseased vessels. METHODS: We compared the vascular images obtained at 7T MRI with conventional MRIs (1.5T and 3T) in the healthy subjects and we also examined the microvascular images in hypertensive and stroke patients, which were also compared to those in healthy group. Several clinical images were also obtained with 7T MRA in the patients with arteriovenous malformation, arterial dissection and occlusion. RESULTS: Microvasculature in hypertensive and stroke patients was enormously different from those of the age-matched healthy subjects. The comparison with conventional angiographic techniques, such as lower field strengths and digital subtraction angiography (DSA), also showed the 7T MRA images had better vessel contrast as well as higher sensitivity to tiny micro vessels. CONCLUSION: Taking the advantage of the ability of 7T MRA to directly visualize microvascular structures in vivo would provide the great potentials for various angiographic research fields as well as a direct visualization of microvasculature with respect to the vascular diseases. Therefore, we hope that 7T MRA could replace the conventional angiographic methods, including contrast enhanced imaging modalities, such as CE MRA, CTA, and DSA, before long. REFERENCES: 1. Duyn JH, et. al., PNAS 2007; 11796 2. van der Zwaag W, et. al., Neuroimage 2009; 1425 3. Cho ZH, et. al., Stroke 2008:1604 4. Kang CK, et. al., MRM 2009:136


7.9 Web Based MRA Protocols Hwayoung Kate Lee MD, Satre Stuelke MD, Michelle Cerilles MD, Martin R Prince MD

PhD Cornell and Columbia Universities, New York, NY

Purpose: Magnetic Resonance (MR) scanning relies heavily on generic protocols typically based upon the organ of interest. MR Angiography (MRA) studies however, are typically more complex examinations which require a great variety of protocols for each vascular territory and frequent customization. In addition, since MRA is often pushing the limits of the MR technology, these protocols require frequent updating, which can be particularly difficulty for centers that operate multiple scanners. Simply using outdated, generic protocols that may not be attuned to clinicians’ needs leads to suboptimal examinations and mistakes, often necessitating repeat examinations or limited reports which degrade the value of imaging. But maintaining state of the art protocols on every scanner and avoiding the inherent drift caused by unfettered scanner access is challenging. Only the super technologists have the insight to optimize protocols and their skills are in high demand for other challenges. Therefore, we propose an easy web-based method of efficiently establishing, maintaining, sharing and updating protocols in multiple MR scanners by using a USB flash memory device. Methods: First, protocols are exported from an MR scanner and saved onto a USB device. Files containing protocols will then be expanded with a file archive, uploaded to a web site (MRprotocols.com) using File Transfer Protocol (FTP), and a content management system (CMS) is used to organize and display the information. During the process, custom code designed to read the raw code from the scanner is used to create html that can be simply cut and pasted into the CMS. Technologists of any skill level can easily download the protocols off the website and upload into their scanner using a USB flash memory chip. Results: This exhibit will demonstrate a step by step approach in the export and transfer process of scanning protocols. Radiologists and technicians will also receive surveys inquiring about scanning experience prior to and following establishment of individualized protocols in each scanner (i.e., improved image quality, time saved during scanning and avoiding unnecessary communication, clinicians’ level of satisfaction, etc.). Conclusion: This exhibit aims to familiarize radiologists and technicians with a simple web-based way of establishing and transferring a variety of MRA protocols in multiple MR scanners for efficient maintenance and sharing of MRA protocols across multiple MR scanners to promote higher quality and efficiency. References: http://www.mrprotocols.com/ http://www.learnmri.org/


8.1 Compressive Sensing Reconstruction Improves Low-contrast Detectabililty

JD Trzasko, A Manduca, Z Bao, KP McGee, Y Shu, J Huston III and MA Bernstein

Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA Purpose: Compressive Sensing (CS) is a data acquisition and reconstruction method that can accelerate some MRI applications with little compromise in image quality [1, 2]. To date, applications of CS to MRI have often focused on situations where the structure of interest has high contrast [3], such as large enhancing vessels. However, in many MRI applications, low-contrast features are of great clinical interest as well. Examples in MRA include detectability of small vessels (which can be low contrast due to partial volume effects) and some MRA studies where tissue perfusion information is concomitantly extracted. In this work, we show that CS can improve low-contrast object detection (LCOD) with a systematic phantom study.

Methods: The American College of Radiology (ACR) Quality Control (QC) phantom was imaged with our standard daily quality assurance protocol on a 1.5T GE MRI running 14.0 software. The full data set was decimated up to 90% using three different sampling schedules (i.e., elimination of k-space lines): 1) retention of low-frequencies, 2) uniform decimation and 3) random decimation. Each undersampled data set was then reconstructed using three different strategies: 1) zero-filling with root-sum-of-squares combination; 2) generalized SENSE [4]; and 3) compressive sensing (ℓ1-minimization with finite differences sparsity [2]). Each reconstructed image was automatically evaluated using ACR analysis software [5], which operates consistently with ACR guidelines [6] for spoke detection.

Results and Discussion: Both CS and generalized sense outperformed zero-filling at all degrees of undersampling. Examination of the images shows that this is due to the severe aliasing artifacts observed with zero-filing undersampled data. At 60% or higher decimation sampling, however, CS begins to clearly outperform generalized SENSE for LCOD. Examination of the images suggests that this latter effect is mainly due to the noise amplification properties of SENSE. Future work will include application of CS reconstruction to novel trajectories such as the

undersampled shells acquisition [7].

Conclusion: Compressive sensing reconstruction can improve low contrast object detectability, which can serve as a metric to evaluate highly-undersampled imaging applications.

References: 1. Lustig M, Donoho D, Pauly J. MRM 2007; 58: 1182-95. 2. Trzasko J, Manduca A, IEEE Trans. Medical Imaging 2009; 28:106-21. 3. Donoho D, IEEE Trans. Information Theory 2006; 52: 1289-1306. 4. Pruessmann K, Weigner M, Bonert P, Boesiger P. MRM 2001; 46: 638-51. 5. McGee K, Felmlee J, Bernstein M, Ward H, et al., Proc. ISMRM 2007, p. 3302. 6. Phantom Test Guidance for the ACR MRI Accreditation Program (www.acr.org). 7. Shu Y, Riederer S, Bernstein M. MRM 2006; 56: 553-62.


8.2 Accelerating 3D TOF with Compressed Sensing J. Yerly1,2, M. L. Lauzon2,3, Robert J Sevick2,3, and R. Frayne2,3

1Electrical and Computer Engineering, University of Calgary, Calgary, AB, Canada, 2Seaman Family MR Research Centre, Foothills Medical Centre, Calgary Health Region, Calgary, AB, Canada,

3Radiology and Clinical Neurosciences, University of Calgary, Calgary, AB, Canada, 4Physics and Astronomy, University of Calgary, Calgary, AB, Canada

Introduction: Time-of-flight (TOF) angiography is a magnetic resonance (MR) imaging procedure routinely used for the diagnosis of vasculature patency. A challenge of conventional three-dimensional (3D) TOF imaging is the tradeoff between spatial resolution and acquisition time, where higher spatial resolution is achieved to the detriment of longer acquisition time. For instance, the total scan time for a 3D acquisition is Tacq = Nav Ny Nz TR, where Nav, NyNz, and TR are the number of averaged signal acquisitions, the number of phase encodings, and the pulse repetition time, respectively. For pulse repetition time = 30ms, Nav = 1, and a 256×128×50 (Nx×Ny×Nz) acquisition matrix, the total acquisition time per volume, Tacq, is 3 min 12 sec. Doubling the resolution while maintaining the same imaging field-of-view (FOV) results in a scan time of 12 min 48 sec. Several approaches exist for accelerating MR imaging, such as parallel imaging1-4 and compressed sensing2 (CS). These approaches may prove favorable via accurate reconstruction of undersampled k-space datasets, thus potentially allowing reducing the acquisition time. Here, we investigate the potential of improving the spatial resolution using the CS paradigm to acquire and reconstruct vastly undersampled TOF k-space datasets, while maintaining reasonable scan time. Method: On a 3.0-Tesla MR scanner (Signa VH/I; General Electric Healthcare, Waukesha, WI, USA), we modified a 3D clinical TOF vascular sequence to only acquire an undersampled set of k-space phase encodes in the ky-kz plane (Figure 1a). To satisfy the CS requirement of incoherent aliasing interferences due to undersampling, the phase encode locations were randomly selected based on a probability density function (PDF) to ensure selection of more samples near the centre compared to the periphery of k-space (Figure 1b). Using an 8 channel head array coil, we acquired a dataset by 10× undersampling the k-space with the following parameters: repetition time (TR) = 30ms, echo time (TE) = 3.5ms, flip angle 30º, acquisition matrix size = 160×750×400, FOVx×FOVy×FOVz = 8cm×15cm×8cm, and image resolution = 500μm×200μm×200μm. We selected one ky-kz slice in the 3D volume to reconstruct via CS and zero filling (ZF) reconstructions. For the CS reconstruction, we used both the wavelet and image domains as sparse domains and adjusted the regularization parameters accordingly through visual inspection of the reconstructed image. The ZF images were reconstructed with and without sampling density compensation (i.e., multiplying k-space data by the inverse of the PDF). Results: As expected, the ZF approach with density compensation resulted in a sharper but noisier image when compared to the ZF approach without density compensation (Fig. 1c and 1d). Figure 1e shows the CS reconstructed image, where adequate and judicious selection of the CS regularization parameters not only preserved spatial resolution but also removed most of the noise. Discussions: The CS approach yielded superior reconstruction than both ZF approaches, however the CS reconstruction takes considerably longer. Variable density sampling and CS reconstruction can produce TOF images with moderate-to-high accuracy from significantly fewer k-space samples than suggested by the Nyquist-Shannon sampling theorem. This makes it possible to significantly reduce acquisition time, and allows for high-resolution TOF images. References: 1Blaimer M, et al. Top Magn Reson Imaging 2004; 15: 223.

2Lustig M, et al. Magn Reson Med 2007; 58: 1182.

Figure 1


8.3 A New Compressed Sensing and Magnitude Constraint Based Approach to Acceleration of Phase Contrast Velocimetry

Julia Velikina, Kevin Johnson, Alexey Samsonov Departments of Medical Physics and Radiology, University of Wisconsin-Madison,

Madison, WI, USA Introduction: Phase contrast (PC) imaging is an important quantitative MRI technique that allows to measure flow velocities in blood vessels and to derive related hemodynamic parameters such as pressure gradients and wall shear stress. However, the necessity to use flow encoding in several directions proportionately increases the scan time. The resultant scan time penalty makes acquisition of fully sampled time-resolved PC data infeasible for some applications that require a breath hold or otherwise limited scan time. Conventional reconstruction from undersampled data results in imaging artifacts and inaccurate flow measurements. Previously, a compressed sensing (CS) approach was proposed (1) for acceleration of PC velocimetry which relied on sparsity of complex difference and individual directional images. However, due to concomitant gradients, eddy currents, and partial echoes, background phases may differ significantly for different velocity encoding directions, thereby violating the assumption of sparsity of the complex difference images (Fig. 1). Nevertheless, this phenomenon does not affect magnitude images whose difference for different velocity encoding directions is still sparse (Fig. 1) as was observed in our previous work (2). We exploit this observation to propose a new approach to separate estimation of image magnitude and phase for accelerated PC velocimetry. Theory and Methods: Magnitude images for all velocity encoding directions are obtained by minimizing the following functional: min ∑ ∑ , where , 1, … , , is a vector of magnitudes for all of available velocity directions,

are diagonal matrices of estimated image phases for each velocity direction, is the encoding matrix comprising both Fourier terms and coil sensitivities, is measured data for each direction, and

is a regularization parameter. For the first iteration, phase is assumed to be zeros or is obtained from low resolution image estimates for each velocity direction. Once a magnitude estimation is obtained, we update the phase component by solving min ∑ exp .Then magnitude estimation is repeated with the new phase estimate and so on until convergence. The proposed algorithm was implemented using iteratively reweighted least squares algorithm (3) for the CS minimization part of it and Newton-Raphson method (4) for phase estimation. The algorithm was tested on a realistic brain phantom supplied with different image phases for the two velocity encoding directions. The k-space data corresponding to radial acquisition trajectory with an undersampling factor of 7 was generated for 4 coil receivers. Non-constant image background phase was added to each velocity encoding directions to simulate realistic imaging situation. Results and Discussion: In our simulations, the algorithm converged after three alternating estimations of magnitude and phase yielding images with significantly improved image quality. We observed reduction of streaking (aliasing) artifacts indicating that algorithm enables higher acceleration factors than with parallel MRI alone. Simultaneously, resolution and g-factors were improved compared to standard SENSE reconstruction The observed benefits (reduction of streaking, g-factor and resolution improvement) was possible

because of better conditioning of the new method due to utilization of prior knowledge about sparsity to constrain the reconstruction. In this work, 1D velocimetry has been utilized. More image reconstruction quality improvement is expected with 3D velocity encoding where information will be shared between 4 images. The present method may be an efficient means of improving image quality in PC velocimetry with radial acquisition geometry and is expected to improve g-factor for Cartesian acquisitions as well. References: [1] King K, et al. ISMRM 2009, p. 2817. [2] Samsonov A, et al. ISMRM 2007, p. 149. [3] Wohlberg B, et al. IEEE SPL 2007;14:948. [4] Tjalling J., SIAM Review 37 (4), 531–551, 1995.

Figure 1. Magnitudes of images in two velocity encoding directions. The complex difference image is not sparse while the difference of magnitudes is largely sparse and hence is amenable to compressed sensing reconstruction.


a) Aliased Axial Slices b) Synthesized Axial Slices

Figure 1: Axial slices at two spatial locations of a) R=2 accelerated data with no ARC and b) R=2 accelerated data after ARC processing.

8.4 Parallel Imaging with Hybrid 3D Radial Acquisition for HYPR Reconstruction

L. Keith1, K. Wang1, J. Holmes2, F. Korosec1,3

1Medical Physics, University of Wisconsin, USA, 2Applied Science Lab - GE Healthcare, Madison, WI, 3Radiology, University of Wisconsin, USA

Purpose HighlY contstrained BackProjection (HYPR) [1] has been utilized as a post processing reconstruction method for a variety of imaging applications, including contrast enhanced MR angiography (CEMRA). In the lower extremities, it has been shown that HYPR reconstruction allows for improved spatial and temporal resolution compared to view sharing reconstructions like TRICKS [2]. Both hybrid 3D radial (SOS) [3] and Vastly undersampled Isotropic Projection Reconstruction (VIPR) [4] have been studied as possible k-space trajectories for CEMRA exams of the lower extremities [5]. Each trajectory has its own advantages and limitations. A previously presented advantage of the VIPR acquisition is the high, naturally isotropic spatial resolution, whereas one limitation of the SOS trajectory has been decreased through plane resolution in order to maintain high temporal resolution. In this work, we apply a k-space based parallel imaging algorithm (ARC) [6] to the slice encoding direction of a SOS acquisition to achieve through-plane resolution equal to that achievable with a VIPR acquisition. Methods The volunteer shown was imaged on a 3T MR750 scanner (GE Healthcare) with a 32 channel torso coil. Gadolinium based contrast was administered intravenously at a rate of 3 ml/s. The contrast volume per injection did not exceed 0.1 mmol/kg. Prior to injection, a fully sampled, non-accelerated, mask image was obtained. The central 16 slice encodings for each projection angle of the mask data served as the auto-calibration lines for the synthesis of subtracted k-space data. A 2D kernel of 5 x 7 was used for the ARC algorithm. An acceleration factor of R = 2 in the A/P direction was used for the stack of coronal slices, leading to a spatial resolution of 0.9375 x 0.9375 x 1.0 mm. HYPR reconstruction of this data with 20 projections per frame would yield a temporal resolution of 6 seconds per frame. Results and Discussion Non-time resolved, composite images are shown below to demonstrate the successful un-aliasing of accelerated data (axial slices) and the improved spatial resolution (sagittal MIPS). The ARC reconstruction successfully un-wrapped the aliasing from the accelerated data set, Figure 1. Figure 2 shows the high, 1.0 mm through plane resolution achievable with parallel imaging while conserving temporal resolution. An R=2 acceleration factor will allow for both improved slice thickness and temporal resolution.

References 1. Mistretta C, et al. MRM 55:30-40;2006. 2. Wu Y, et al. Procs of 16th ISMRM Meeting 2008, p20. 3. Peters D, et al. MRM 43:91-101;2000. 4. Barger, et al. MRM 48:297-305;2002. 5. Keith, et al. Procs of 18th ISMRM Meeting 2010. 6. Brau AC, et al. Procs of 14th ISMRM Meeting 2006

Figure 2: Sagittal MIP of single leg of R=2 accelerated SOS acquisition with through plane resolution of 1.0 mm (a) and a magnified view of the vascular structure (b).


8.5 3D Time-Resolved MRA of Lower Extremities using Interleaved Variable Density Sampling, Parallel Imaging and Cartesian HYPR

Reconstruction

1aJ. Holmes, 2aK. Wang, 1aR. Busse, 1bP. Beatty, 1aJ. Brittain, 2bC. Francois, 2b,cS. Reeder, 2aL. Keith, 2aY. Wu, 2a,bF. Korosec

1Applied Science Lab, GE Healthcare, 1aMadison, WI, 1bMenlo Park, CA; 2aMedical Physics, 2bRadiology, 2cBiomedical Engineering, University of Wisconsin-Madison,

Madison, WI Purpose: To simultaneously improve spatial and temporal resolution of 3D time-resolved CE-MRA of lower extremities using Cartesian interleaved variable density (IVD) sampling [1], data driven parallel imaging (PI) [2,3] and a HYPR constrained reconstruction [4-6]. Methods: Imaging was performed using a 3d SPGR sequence with TR/TE=5.6/2.0 ms, BW=±62.5 kHz, and flip angle = 30o. During data acquisition, the k-space for each time frame is undersampling in the ky-kz plane by a factor of 36 (6 using PI and another factor of 6 using IVD), shown in Fig. 1. The ARC parallel imaging method [3] was integrated with a Cartesian multiplicative constrained reconstruction related to HYPR [6] to both unfold the aliased image and suppress incoherent artifacts caused by IVD. Imaging parameters include: 1.0mm isotropic resolution with FOV of 480 (S/I) × 320 (L/R) × 120 (A/P) mm3, 32 time frames were resolved at 5.3 sec per frame. Images were acquired on a clinical 3T scanner with a 32-channel coil. Results: Progression of the contrast bolus through the peripheral vasculature was well depicted (Fig. 2 a-c, arrows) in coronal MIP images from three consecutive time-frames (a-c) of a healty volunteer. In addition to the high temporal resolution, the isotropic spatial resolution allows for improved vessel depiction when reformatting the data (Fig 2 d, Sagittal reformat). Further, a venous phase image (Fig 2e) and enlargement allow for visualization of two venous valves (Fig 2 f, arrows). Conclusion: The combination of IVD, PI and Cartesian HYPR reconstruction enables increased under-sampling (acceleration) while maintaining image quality, thus improving the spatial and temporal resolution that can practically be achieved in 3D time-resolved MRA of lower extremities. References: [1] Busse et al., ISMRM 2009, p4534. [2] Griswold et al. MRM 47:1202 (2002). [3] Brau et al. MRM 59:382 (2008). [3] Mistretta et al. MRM 55:30 (2006). [4] Johnson et al. MRM 59:456 (2008). [5] Wang et al. ISMRM 2010, p352

Figure 1. Sampling pattern for an individual time frame (×6 PI, ×6 IVD).


Figure 1. Coronal (A) and sagittal (B) extended-FOV MIPs of the calves and feet. The sagittal MIP is of the right leg only for clarity. Note the sharpness of small vessels and the 3D nature of the acquisition. These MIPs were interpolated to 0.75 mm isotropic sampling.

A B

8.6 Time-Resolved Calf-Foot 3D Bolus-Chase MRA Casey P. Johnson, Eric A. Borisch, Petrice M. Mostardi, James F. Glockner, Phillip M.

Young, Stephen J. Riederer MR Research Laboratory, Mayo Clinic, Rochester, MN

Purpose: Diagnostic contrast-enhanced MRA is challenging in the calves and feet. It requires significant spatiotemporal resolution to resolve small vessels, avoid venous contamination, and map complex flow patterns. CAPR combined with 2D SENSE and 2D homodyne acceleration has been previously used for imaging the lower extremities. In the calves, CAPR has been used to routinely acquire arteriograms with 1.0 mm isotropic spatial resolution and frame times of 5.0 sec (5 to 18 sec temporal footprint).[1,2] In the feet, CAPR has successfully been used to acquire high-quality arteriograms with 0.75 x 0.75 x 0.9 mm3 spatial resolution and a 6.8 sec frame time (27 sec temporal footprint).[3] However, these single-station acquisitions have limited longitudinal coverage: typically 40 cm at the calves and 30 cm at the feet. The aim of our work is to use CAPR to image both the calves and the feet with a single contrast injection using a stepping table approach. This two-station CAPR technique has been previously demonstrated in bolus chase MRA studies of the thighs and calves.[4,5] Here we apply similar methodology with unique scan parameters at each station to image an effective longitudinal FOV of 60 cm with coverage from the popliteal to the pedal arteries. Real-time reconstruction of the CAPR time frames is used to precisely trigger table motion from the calf to the foot station. Methods: The calves and feet of three healthy volunteers were imaged in accordance with an IRB-approved protocol. The volunteers were imaged on a 3T GE Signa v14x MRI system with a fast coronal GRE sequence. Two 8-channel receive arrays were used, one placed circumferentially around the calves and the other similarly around the feet. Only one array was activated at a time. The calf FOV was 32 x 32 x 13.2 cm3 with a 400 x 320 x 132 sampling matrix (0.8 x 1.0 x 1.0 mm3). The foot FOV was 30 x 21.6 x 24 cm3 with a 400 x 288 x 240 sampling matrix (0.75 x 0.75 x 1.0 mm3). 8x 2D SENSE and 1.9x 2D homodyne were used to accelerate both stations, yielding a net acceleration of 15.2x. The calves were imaged with N8 CAPR, yielding a 2.5 sec frame time (19 sec temporal footprint), and N4 CAPR was used to image the feet with a 6.7 sec frame time (25 sec temporal footprint). Following a localizer and SENSE calibration scan, subtraction masks were acquired and 20 mL of contrast material (Multihance®) followed by 20 mL of saline flush was intravenously injected at 3 mL/sec. Time frames were reconstructed in real-time and maximum intensity projections (MIPs) were displayed on the scanner console via a graphical user interface (GUI). Upon observing contrast material traverse the calf station, the operator triggered the table to move 30 cm to the foot station. Results: Good quality arteriograms were acquired in both stations for all volunteers. The table was successfully triggered in all studies, and venous contamination was avoided at the distal station. Fig. 1 shows coronal and sagittal extended-FOV MIPs consisting of the last calf frame and the second foot frame for one volunteer. The arteries are clearly visualized in both stations. However, there is signal drop-out at the inferior end of the calf station, which is attributed to inadequate receiver coil coverage and should be correctable. In the first study (not shown), the volunteer moved his foot between the calibration and time-resolved scans, which led to improper unfolding of a portion of a superficial artery. This problem was avoided in the subsequent studies by better restraining the feet. Conclusion: Two-station time-resolved bolus chase MRA with real-time triggering of table motion has been successfully applied to imaging of the calves and feet. Venous contamination was avoided and all major arteries were clearly visualized except at the interface of the two stations. Future work will focus on improving the continuity of vessel signal across the FOV and extending the acquisition to three or more stations. References: [1] Haider CR, Radiology 2009, 253:831-43. [2] Haider CR, MRM (in press). [3] Haider CR, ISMRM 2009, #271. [4] Johnson CP, ISMRM 2010, #3760. [5] Johnson CP, MRM (in press).


8.7 HYPR CE: High resolution 4D contrast enhanced MRA using single dose, dual injection and constrained

reconstruction Yijing Wu, Kevin Johnson, Steven Kecskemeti, Charles Mistretta, Patrick Turski

Departments of Medical Physics and Radiology, University of Wisconsin, Madison, WI INTRODUCTION: Time resolved contrast-enhanced magnetic resonance angiography has been widely used to evaluate the hemodynamics of the vascular structure [1-2]. However, there are tradeoffs between temporal and spatial resolution. Low dose HYBRID HYPR technique [3] is able to decouple the high spatial resolution and SNR, which require relative long scan time, from high temporal resolution, which demands for fast data acquisitions, and used HYPR constrained reconstruction to obtain a time series of images with high temporal and spatial resolution and high SNR using contrast dose as little as 1 ml. One of the disadvantages of the HYBRID HYPR technique is that the composite image (either phase contrast or TOF) is sensitive to flow. In the areas with complex/slow flow, there might be signal drop-off, which in turn will degrade the final images. In this work, we present a novel method (HYPR CE), where a small volume of contrast (~ 2 ml) will be used for the time-resolved temporal weighting images and a standard single dose will be used for the following high resolution contrast enhanced scan as the composite. By utilizing the HYPR constrained reconstruction, the final images will be high temporal and spatial resolution and high SNR without any flow-sensitive artifacts and significant increase of contrast dosage. METHODS AND RESULTS: HYPR CE has been tested in five volunteers. Dynamic weighting images were acquired using the multi-echo VIPR sequence with a small volume of contrast material. Imaging parameters were: TR/TE = 3.5/0.4 ms, FA=30o, BW=125 kHz, 4 half echoes, acquisition matrix = 128, frame rate = 2/s. 2 ml contrast was injected at 3 ml/s with 25 ml saline flush. After the dynamic acquisition, a fluoro-triggered high resolution contrast enhanced MRA was acquired as the spatial constraint. Acquisition parameters were: TR/TE=5.4/1.9 ms, acquisition matrix = 384x384x160, slice thickness = 1mm. 2x2 parallel imaging was applied in both phase and slice encoding directions. Scan time was about 90 sec. A single standard dose of contrast was injected at 2 ml/s using fluoro-trigger technique. Final images were reconstructed using the HYBRID HYPR technique [3] to achieve the high temporal resolution and high spatial resolution simultaneously. Preliminary results show that HYPR CE is able to provide high temporal and spatial resolution and SNR without any signal bias from the composite image. DISCUSSION: HYPR CE utilizes high resolution contrast enhanced MRA as the spatial constraint to reconstruct the time-resolved contrast enhanced image series without significant increase of contrast material. Small volume of contrast in the dynamic acquisition provides a shorter bolus, which in turn improves the arterial venous separation. Iterative reconstruction [4-5] can be applied to further improve the reconstruction accuracy. Both dynamic weighting images and the high resolution contrast enhanced constraining images do not depend on the sampling strategy and can be acquired with the best available sequences. Usually, motion is not expected to happen between scans within such short scan time (totally less than 4 mins). However, if motion occurs image registration should be performed before the HYBRID HYPR reconstruction. In the future, high resolution CE VIPR with parallel imaging and matched filter reconstruction will be explored as a substitute for the fluoro-triggered CE MRA to simplify the clinical procedure. REFERENCE: 1. Haider, et al., MRM 2008;60:749-760. 2. Cashen, et al., MRM 2007;58:962:972. 3. Wu, et al., ISMRM 2010, p3765. 4. Griswold, et al., ISMRM 2007, p188. 5. Seiberlich, et al., ISMRM 2010, p3489.

Figure: Time resolved contrast enhanced MRA using HYPR CE technique. Spatial resolution is 0.57x0.57x1.0 mm3. Frame update time is 0.5 s. Temporal reconstruction window is 0.75 s.


9.1 Self-Gated Free Breathing 3D Coronary Cine Imaging With Simultaneous Water and Fat Visualization

Jing Liu, Thanh D. Nguyen, Jonathan Weinsaft, Martin R. Prince, Yi Wang Weill Medical College of Cornell University, New York, NY

Purpose: To develop a new imaging technique for acquiring 3D coronary cine water and fat separated images during free breathing without external respiratory or cardiac gating. Method: The sequence has multi-echo radial acquisition in-plane and Cartesian encoding through-plane [1]. The multi-echo data sets acquired at different echo times were used to separate water and fat signals [2]. Data were acquired continuously to avoid interrupting the SSFP steady state and to generate cardiac phase resolved images, eliminating the need for patient specific trigger delay as in conventional ECG gated coronary MRA. The cardiac phase presenting the coronary arteries best could be selected retrospectively. The sequence does not require dedicated preparation pulses such as navigator, T2-prep and fat-suppression pulses. A golden-ratio-based angle profile was used to allow flexible view sharing and provide high temporal resolution [3,4]. Respiratory and cardiac motion information was extracted from the image data itself [1], and external respiratory or cardiac gating was not required. Typical 3D cine coronary MRA parameters were: TR/TEs=5.0ms/0.3/1.6/2.9ms, FA/BW/FOV=40°/±125kHz/26cm, matrix=256x256, 14~16 slices, slice thickness=3mm, on a 1.5 T GE EXCITE 14M4 scanner. Temporal resolution was 70~80 ms and scan time was 5 min. The respiratory self-gating efficiency was 50%. Conventional breath-hold ECG triggered 3D Cartesian images were acquired for comparison. A total of ten healthy volunteers were imaged. Both RCA and LAD were imaged in randomized order. 3D breath-hold Cartesian method was applied for comparison, with an acquisition window of 200 ms during 24 heartbeats and spatial resolution is 1x1.6x3 mm. We further proposed a novel method for improving the contrast of coronary MRA by exploiting the fat image. In the water image, the coronary artery has bright signal Swb and the surrounding myocardium has low signal Sm; in the fat image, the coronary artery has near zero signal Sfb and the surrounding fat has strong signal Sf. With SSFP sequence, we have Sf>Swb>Sm>Sfb, thus the contrast of the coronary artery in the fat image is stronger than that in the water image. Based on this, we proposed a method to enhance the contrast in the water image by masking the complement of the fat image. Results and Discussion: Fig. 1 shows the right coronary water and fat cine images. The artery appears nicely at a central phase (dashed box) in both water and fat images, and gets blur away from the central phase. This demonstrates that the best visualization of the coronary artery is sensitive to time. The coronary artery contrast in the water image (Fig. 2a&e) are improved by combining the complement of the fat image (Fig.2b&f), as shown in Fig. 2 c&g. 3D breath-hold images are shown in Fig. 2d&h for comparison. Water and fat separation worked well even by ignoring the local field inhomogeneities. Further improvement may be expected by including the local inhomogeneities. This proposed method worked robustly for imaging both RCA and LAD. Higher dimensional self-gating and motion correction are under investigation. Further research on optimizing the combination of the fat image is also desired. Conclusion: This abstract proposes a new 4D coronary MRA technique, which does not require breath-hold, or external respiratory and cardiac gating, or dedicated preparation pulses, and generates cardiac water and fat cine images in reasonable scan time. References: 1. J Liu, et. al., MRM, 63, p194. 2. GH Glover, et. al., MRM, 18, p371. 3. S Winkelmann, et. al., IEEE-TMI, 26, p68. 4. J Liu, et. al., IEEE-TMI, 25, p148.

Fig. 1 Coronary water and fat cine images obtained from a healthy volunteer. MIP images of two slices at five sequential cardiac phases are shown.

Fig. 2 Images acquired with the proposed self-gated free-breathing technique (ab&ef) achieve improved coronary artery contrast by combining the fat image (c&g vs a&e). Images acquired with conventional breath-hold method are also shown (d&h).

a) b) c) d)

e) f) g) h)


9.2 Integrating High Spatial-Resolution, 3D Whole-Heart Viability Imaging and Coronary MRA at 3 Tesla

Qi Yang1, Kuncheng Li1, Xiaoming Bi2, Feng Huang4, Renate Jerecic3, and Debiao Li5 1. Radiology Department, Xuanwu Hospital, China 2. Siemens Medical Solutions USA 3.

Siemens MR Collaboration NE Asia 4.Invivo Corporation 5. Radiology Deaprtment, Northwestern University

Purpose: To evaluate whether contrast-enhanced whole-heart coronary MRA (CMRA) can characterize myocardial infarct (MI) with patterns similar to those obtained by conventional 2D MR technique. Methods and Materials: 50 patients with suspected coronary artery disease who were scheduled for coronary angiography (CAG) underwent CMRA at 3T (MAGNETOM Tim Trio, Siemens) after informed consent was obtained. For image acquisition an ECG-triggered, navigator-gated, inversion-recovery prepared, segmented gradient-echo sequence was used. Contrast agent (0.15 mmol/kg body weight, MultiHance, Bracco, Italy) was intravenously administered at a rate of 0.3 ml/sec. For comparison, reference standard 2D segmented, breath-hold phase-sensitive inversion-recovery DE-CMR infarction imaging was performed in the 2-chamber, 4-chamber and multiple short-axis views. For MI image analysis, standard 17-segment AHA classification system was used. The correlation of MI area measured by CMRA and 2D PSIR images was performed, and the agreement of MI measurements was assessed by using the Bland and Altman plot. Results: Whole-heart CMRA was successfully completed in 46 of 50 (92%) patients. The averaged imaging time was 6.9± 1.8 min. Whole-heart CMRA correctly detected MI in 12 patients and correctly ruled out MI in 34 patients. The MI regions measured by Whole-heart CMRA and 2D PSIR were highly correlated (r=0.89, P<0.01). Example images are shown in Fig 1. Conclusion: The information on tissue characterization it provides can be obtained almost for free when Whole-heart CMRA is performed for the purpose of coronary imaging. Reference:1. 1. Yang Qi, Li k, et al. J Am Coll Cardiol, 54: 69-76, 2009. 2. 1.Bi X, Li D, et al. Proceedings of 15th annual ISMRM, Berlin.

Fig. 1: 3T whole-heart CMRA images of a 59 year-old patient. Curved MPR CMRA image (a) detects a significant LAD stenosis (green arrow). 3D Reformatted viability image (b,c) shows transmural hyperenhancement of the anterior septal wall and the apex (red arrows head) suggesting previous myocardial infarction. (d) CAG image confirms the stenosis on proximal LAD.


9.3 Removal of Eddy-Current Effects in Multiphase Cardiac Flow Imaging

Pan-Ki Kim, Sang-Heum Cho, Jin-Ho Park, Chang-Beom Ahn Department of Electrical Engineering, Kwangwoon University, Korea

Purpose Cardiac flow imaging is a quantitative method to measure the flow velocity in the heart and arteries. Eddy currents are one of the main obstacles in the quantitative evaluation of the flow velocities since they introduce additional phases on the velocity encoded phases. In this paper we propose a technique to remove the eddy-current induced phases by a post-processing. Methods Two bipolar gradients with opposite polarities are used to encode the velocities of blood flow [1]. Phase reconstruction is made for each measurement and phase differences are taken to obtain velocities. The eddy-current induced phases are hard to remove accurately by a pre-calibration of eddy currents since they are related to various environmental and experimental parameters such as subject imaging region, slice orientation, repetition time, echo time, etc. Although they have such varying character, they may be time invariant during a series of multi-phase cardiac flow imaging once the experimental and environmental parameters are set. On the other hand, the flow velocities are time variant depending on the cardiac phases. Using these characteristics, the standard deviations of the eddy-current induced phases are zero as shown in Eqs.(1) and (2), which may be used in the classification of the stationary regions irrespective of the existence of eddy currents.

),(),(),( yxEyxVayx kk +⋅=φ (1)

)),(()),(()),(()),(( yxVSDayxESDyxVSDayxSD kkkkkkk⋅=+⋅=φ (2)

The proposed technique is to measure the eddy-current induced phases in the stationary regions, which are extended to the entire imaging region by an expansion of spherical harmonics of lower orders, and then are removed to obtain the velocity map free from eddy current effects. Results Multi-phase cardiac flow images are obtained at 1.5T whole body MRI. One of a series of multiphase velocity maps obtained before the removal of the eddy-current induced phases is shown in Fig.1(a), where the eddy-current induced phases are existent as seen in the stationary regions at the bottom of the image. By the proposed method, such phases are removed in Fig.1(b). Removal of the eddy-current induced phases is important in the quantitative evaluation of flow velocities in the cardiac and vascular flow imaging for various diagnostic purposes.

Fig.1 Velocity maps before (a) and after (b) removal of the eddy-current induced phases by the proposed technique.

Conclusion Eddy-current induced phases are successfully isolated and removed from the velocity encoded phases in the multi cardiac phase flow imaging, which is important in the quantitative flow evaluation. The method appears to be robust to noise or patient motions. References [1]M. Bernstein, K. King, X. Zhou, Handbook of MRI Pulse Sequences, Elsevier, New York, 2004.


9.4 Left ventricular MR velocity mapping: radial and long-axis dyssynchrony

D. Föll1, B. Jung2, E. Schilli1, F. Staehle2, Ch. Bode1, J. Hennig2, M. Markl2

1 Dept. of Cardiology and Angiology & 2 Radiology, Medical Physics, University Hospital Freiburg Germany

Introduction: Left ventricular (LV) dyssynchrony has prognostic impact in heart disease1,2. However, it is still debated which imaging modality and myocardial velocity component is most suitable for the analysis of synchrony3. Magnetic Resonance (MR) Tissue Phase Mapping (TPM) allows for a complete segmental analysis of all myocardial velocity components (radial, long-axis, rotation) with high temporal resolution. Our aim was to compare the value of dyssynchrony parameters based on systolic and diastolic timing of radial and long-axis velocities. Methods: We acquired myocardial velocities in 58 healthy volunteers (3 age-groups) and 37 patients (18 with hypertensive heart disease, 19 with dilated cardiomyopathy (DCM), including 7 with left bundle branch block) using MR-TPM4 (spatial/temporal resolution 1.3×1.3mm/13.8ms; venc =15cm/s resp. 25cm/s). Four parameters of LV dyssynchrony were analyzed: standard deviation over LV 16-segment model for times-to-peak systole (TTPSys) and diastole (TTPDia) for both radial and long-axis motion (see figure 1). Results: Diastolic dyssynchrony (p<0.05) correlated with age. Systolic radial dyssynchrony correlated with age only in women (correlation coefficient (CC) =0.53 vs CC=0.001 in men).Radial dyssynchrony was increased in women compared to men (systolic 30.5±6.5 vs 22.2±6.2; diastolic 37±3.6 vs 25.5±5.4) in the oldest age-group. Systolic radial and diastolic dyssynchrony correlated significantly with LV mass (p<0.05) and function (p<0.01). Systolic radial and diastolic long-axis dyssynchrony were significantly altered in all patients compared to the age-matched controls (p<0.01) (see figure 2). In contrast, systolic long-axis dyssynchrony did not differ between volunteers and patients. Conclusion: LV dyssynchrony parameters were influenced by age, LV mass or function to various extent and significant gender differences were observed. In our cohort, diastolic and radial systolic dyssynchrony were superior compared to systolic long-axis dyssynchrony to discriminate between patients and healthy controls. References: 1Shamim W et al.,Int J Cardiol1999;70:171-8,2 Sanderson JE , JACC 2007;49:106-108,3 Chung et al. Circ 117: 2608-16,4 Jung et al., J Magn Reson Imaging 2006; 24: 1033-9.

Fig. 1: Radial (vradial) and long-axis (vlong-axis) velocities were acquired in basal, midventricular, and apical short axis slices. B: Data for each subject were mapped onto an AHA 16-segment model and used to derive systolic (TTPSys) and diastolic (TTPDia) times-to-peak velocity C: Systolic and diastolic dyssynchrony parameters

Fig. 2: Systolic( left) and diastolic (right) left ventricular dyssynchrony in patients compared to age-matched healthy controls. (* indicates significant differences). Bar plots: mean (black filled rectangle), median (red line), and standard deviation (error bars), [25% 75%] data range (open rectangles).


9.5 Coronary Vein Motion in Patients Undergoing Cardiac Resynchronization Therapy:

Implications for MR Coronary Venography John N. Oshinski, Ph.D., Pierre Watson, B.S., Jonathan Suever, B.S.

Departments of Radiology and Biomedical Engineering, Emory University School of Medicine and Georgia Institute of Technology, Atlanta, GA

Purpose: The purpose of the study was to examine the motion of the coronary veins in patients with CAD and patients scheduled to undergo CRT. We hypothesized that the location during the cardiac cycle of periods of low motion of the coronary veins would differ between patients with CAD and patients with heart failure undergoing CRT. Methods: Steady-state free procession cine images were acquired from two groups: 1) thirteen patients with CAD (had previous MI > 6 months ago) and 2) thirteen patients scheduled to undergo CRT (NYHA class III heart failure, QRS duration >120 msec, EF < 35%). The frame-by-frame displacement of the center of mass and cross-sectional area of the coronary sinus was tracked in two-chamber, vertical long axis cine images. Periods of low motion were defined as having frame-to-frame displacement of less than 0.5 mm. Results and Discussion: 93% (14/15) of CAD patients had their longest period of low motion in mid-diastole, consistent with previous studies. 100% (15/15) CRT patients had their longest period of low motion in systole. Typical curves of displacement of the coronary veins over the cardiac cycle in a CAD patient and CRT patient are shown in the figure below. In 21% of the CRT patients, there was no separate diastolic low motion period. The CRT patients had a longer period of low motion than the CAD patients (32% of cardiac cycle versus 25% of cardiac cycle, p=0.003). In 93% of all subjects, the cross-sectional area of the coronary sinus was larger in systole than in diastole. The larger size of the veins in systole could be an advantage in making 3D venograms gated to peak systole. Conclusion: The temporal location in the cardiac cycle of periods of low motion of the coronary veins differs between patients with CAD and patients undergoing CRT. Patients undergoing CRT had a low motion period located in systole, therefore 3D images of the coronary veins should be acquired at this period systolic low motion. Each patient’s low motion periods should be categorized using cine before imaging the coronary veins to ensure the correct period is being utilized to minimize motion artifacts. References 1. Wang Y et al. Radiology 1999. 2. Chiribiri A et al. Invest Rad 2008. 3. Johnson KR et al. JCMR 2004. 4. Nezefat R et al. MRM 2007.

CRT CAD

Figure. Displacement of the coronary sinus over the cardiac cycle is shown in a typical CAD patient and a typical CRT patient. The red crosses show the frames that are low periods. The gray bars show the temporal position of the low motion periods.


9.6 Assessment of Myocardial Perfusion --- Comparison of CT, MR and NM ---

Mochizuki T, MD, Kurata A, Kido T, Kido T, Higashino H, Hosokawa S, Kikuchi K, Miki H, Okayama H, Higaki J and Murase K.

Radiology and Cardiology, Ehime University School of Medicine. Toon City, Ehime, and Laboratory of Medical Image and Information Analysis, Osaka University Japan

PURPOSE Coronary MR/CT angiography has become a clinical tool in the assessment of coronary artery disease (CAD). As well as the evaluation of coronary stenosis, myocardial perfusion reserve is also important to make treatment strategy and to predict prognosis. Although MR (first pass and delayed enhancement) has advantage in the assessment of myocardial perfusion over CT, CT has higher spatial resolution. Perfusion CT may have caught up with MR in the assessment of myocardial perfusion and perfusion reserve. Therefore, we compared diagnostic power of CT and MR in comparison with Nuclear Medicine (NM), in the assessment of myocardial perfusion and perfusion reserve. METHODS Patients with suspected CAD, who performed CT, MR and NM were enrolled in this study. MR system used was a 3T-MR with 32-channel coil. CT-systems used were 256 and 64 multi-slice CT (MSCT). SPECT system used was a 3-headed one. In this paper, we conducted two different protocol, (1) dynamic (1st pass) studies with and without ATP-stress, and (2) delayed enhancement. RESULTS and DISCUSSION Although contrast of MR was superior to CT, ATP/non-ATP dynamic (1st pass) CT had similar diagnostic power with a help of higher spatial resolution. Image fusion of coronary tree by CT and myocardial perfusion by NM was helpful to depict culprit coronary artery in relation to the degree (magnitude) of the decrease in myocardial perfusion and perfusion reserve. In the assessment of delayed enhancement, MR was superior in contrast of hypo-perfusion area, CT could also depict delayed enhancement. CONCLUSION The first pass (dynamic) perfusion CT had similar power compared with MR in the assessment of ATP/non-ATP perfusion and perfusion reserve. MR had advantage in the assessment of delayed enhancement (myocardial viability), however, CT could assess delayed enhancement in many patients.


9.7 ECG-Gating for MRA Grace Choi, Zhitong Zou, Kana Fujikura, Martin R. Prince

Cornell and Columbia Universities Purpose: ECG gating is essential for many MRA sequences and cardiac MRI. However, applying multiple adhesive electrodes to the chest can be tedious, time consuming and may require shaving chest hair. We have developed a reusable pad that holds conductive electrodes such that they press against the back while a patient lays supine; thus creating good electrical contact to the skin without requiring any adhesive. In this work we assess the feasibility and reliability of ECG-gated MRA and MRI with this simplified electrode design. Methods: ECG pad was constructed by embedding 4 radio-translucent carbon electrodes into a foam core surrounded by a flexible waterproof vinyl material. Standard electrode gel was applied and visco-elastic foam was placed between the ECG pad and scanner bed to enhance electrode skin contact pressure. ECG pad was applied to the subjects back opposite the left nipple. 10 experimental subjects were imaged on a 1.5T (GE HDx14.0) using the cardiac array coil. ECG triggered, double inversion recovery, cine SSFP, perfusion and spoiled gradient echo images of the heart were obtained in multiple planes using the ECG pad. Gating signal amplitude relative to baseline noise on the ECG pad signal was compared to traditional multiple adhesive electrode ECG signals. Results: ECG pad signal with a horizontal 4 point lead geometry had comparable quality to traditional multi-electrode ECG signal when subjects were outside the bore. Amplitude of ECG pad T-wave increased same amount as TM-S T-wave when subjects were advanced into center of bore. All sequences evaluated ran with consistent gating using the ECG pad. In all cases the subjects preferred the comfort and convenience of the ECG pad to adhesive electrodes. Conclusion: ECG pad for MRA and MRI produces reliable ECG signal, enables rapid application, and eliminates patient discomfort associated with adhesive lead removal.


9.8 A Novel Approach to ECG-Gated High Resolution Contrast-Enhanced MR Angiography in a Single Breath Hold

Yutaka Natsuaki1, J. Paul Finn2, Randall Kroeker3, Gerhard Laub1 1Siemens Medical Solutions, USA, 2Radiology, University of California at Los Angeles,

USA, 3Siemens Medical Solutions, CAN Purpose: We propose a novel approach to acquire ECG-gated high-resolution contrast-enhanced MR Angiography (ce-MRA) with optimized contrast injection timing and reduced sensitivity to cardiac motion, all within a single breath hold. Methods: Our approach is based on a Cartesian ECG-gated 3D FLASH sequence optimized for ce-MRA. Currently, all in-plane phase encoding steps are acquired in a single R-R interval. The acquisition is then repeated in linear order for all slice encoding values. With this scheme, the total scan time is the average R-R interval multiplied by the total number of slice encoding steps. With short TR times of 2.7ms and typically less than 200 in-plane phase encode steps, the data acquisition window during each heartbeat is much less than the average R-R interval, resulting in a very inefficient acquisition scheme. With our proposed strategy, combinations of in-plane and slice phase encoding steps can be selected, in an effort to acquire as many phase encoding steps as possible during each R-R interval. Parallel imaging and partial Fourier techniques will be applied to further optimize spatial resolution and scan time.

Within the R-R interval, the multiple inner loops are acquired in a saw tooth-like pattern (Fig.1), allowing the center of k-space acquisition (i.e. at ky=0, time-to-center per heartbeat (TTC/HB)) to occur only once and to be in sync with the cardiac motion. By allowing flexibility in inner loop mode (linear or centric), TTC/HB can be further optimized to acquire the center k-space data at a specific cardiac phase. Outer loop mode is also flexible (linear+shifts), and this can be utilized for the overall time-to-center (TTC) optimization to enable optimal contrast enhancement. Results: The sequence was implemented at 1.5T (Siemens Healthcare, Erlangen, Germany) and tested in a series of 5 clinical patients under IRB regulations. The parameters are closely matched with the non-gated counterpart (TR/TE 2.7msec/ 0.9msec, TTC 6sec, FA 30, BW 610Hz/pixel, iPAT 3, image matrix 288x512, slices 130, and voxel res. 1.3x1.0x1.3mm3). Scan time for the gated CE MRA is on the average of 25sec, while the non-gated is 21sec. Preliminary results show improvements in image quality at cardiac region (see arrows on Fig. 2). In patients with regular heartbeats, the proposed technique can further improve the ce-MRA in the cases where cardiac and pulsating motions are prominent. Conclusion: The proposed gated ce-MRA sequence generates superior image quality for cardiothoracic applications with a moderate increase in scan time.

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10.1 Comparison of Renal MRA/CTA and Angiography Data in CORAL Study

Zhang HL, Matsumoto A, Cutlip D, Murphy TP, Cooper C, Dworkin L, Prince MR Purpose: To compare the MRA/CTA and DSA results in patients randomized to angioplasty and stent therapy in the CORAL (Cardiovascular outcomes in Renal Atherosclerosis Lesions) study. Methods: CORAL is a prospective, multi-center study randomizing patients with systolic hypertension and severe renal artery stenosis to either medical therapy or medical therapy with renal artery stenting. Outcomes including death, dialysis, blood pressure control are monitored for ~ 5 years. For patients randomized via MRA or CTA these data were compared to DSA. In addition the results of outside review MRA/CTA analyses were compared to core lab reviews. Results: A total of 133 renal MRA studies and 61 CTAs interpreted locally as significant renal artery stenosis have been reviewed, of which only 87 (65 MRA, 22 CTA) were confirmed to have > 60% stenosis. Other local radiologist errors included failure to identify accessory renal arteries, failure to identify a renal infarct and failure to assess, post-stenotic dilatation, symmetry of enhancement or kidney size. DSA correlation was available for 25 (6 CTA, 19 MRA) patients, 31 arteries, randomized to stent. CTA correctly diagnosed the severity of luminal stenosis in 7 of the 8 renal arteries with 1 false positive, accuracy = 88%. MRA correctly identified 22 hemodynamically significant lesions in 23 arteries with an accuracy of 96%. MRA/CTA overestimated stenosis severity in 22 of the 31 arteries (71%). Conclusion: CORAL is an important study for assessing how to treat renal artery stenoses and thus far, MRA/CTA has proven to be accurate methods for identifying patients eligible for study randomization when interpreted by experts at MRA/CTA core laboratory. High number of local radiologist errors, 55% of cases, suggests an opportunity for improving MRA through continuing medical education. Table 1: Accuracy of MRA/CTA on identifying renal artery stenosis using angiography as standard of reference.

# of arteries

False positive Accuracy Average stenosis severity

Core lab Angio MRA 23 1 96% 79% 72% CTA 8 1 88% 67% 69%

Figure 1: Renal MRA showed 90% left renal artery stenosis as compared to 71% stenosis on renal angiography.


10.2 Combined Renal MRA and Perfusion with a Single Dose of Contrast

Hyun J. Jeong1, Parmede Vakil1, James C. Carr2, Timothy J. Carroll1,2

1Biomedical Engineering, Northwestern University, Chicago, IL, USA,2Radiology, Northwestern University, Chicago, IL, USA

Purpose Both anatomical and functional scans are often performed when diagnosing renovascular diseases, requiring two separate contrast injections. With nephrogenic systemic fibrosis (NSF) being associated with gadolinium, a low dose scan is desired. A previously developed 3D MRA technique called Contrast-enhanced Angiography with Multi-Echo and Radial k-space (CAMERA) (1) applies sliding window reconstruction to provide sub-second frame rates in dynamic anatomical analysis of the renal vasculature. The high frame-rates of CAMERA are also beneficial for perfusion analysis. In this study, we present a protocol using CAMERA to obtain both angiographic information in the renal vessels as well as perfusion information in the renal parenchyma with one scan and dose of contrast agent. Materials and Methods The CAMERA protocol is a radial 3D spoiled gradient echo technique with multi-echo acquisition in the partition direction and sliding window reconstruction (2-3). With IRB approval, angiography and perfusion studies were carried out on six healthy volunteers using the CAMERA protocol with the following imaging parameters: echo train length (ETL) =4, number of projection (NP) =192, readout points (NRO=192, 75% fractional echo), FOV=240mm, slices = 32, slice thickness = 3.0 mm, flip angle =30°, TR=6.02ms. TEs= 1.45, 2.48, 3.51, 4.54 ms. Images were acquired in the coronal plane. A single dose (0.1 mmol/kg) of Magnevist was injected for each study, and images were acquired on a Siemens 3T-Trio scanner (Siemens Medical Solutions) using a phased

array body coil. The CAMERA protocol with sliding window

reconstruction produced angiograms with frame rates of approximately 1.7 frames/s. Full 3D volumes of 32 slices were obtained for each frame and coronal maximum intensity projections (MIPs) were obtained for perfusion analysis and angiography, respectively. Results The MRA images and perfusion maps were successfully acquired for 5 of the 6 volunteers. One of the six MRAs suffered from mild motion artifacts due to the inability of the volunteer to follow breath hold instructions. Figure 2 shows a time series of the typical time-resolved renal MRA using CAMERA. Sequential filling of the aorta, renal arteries, and segmental vessels can be seen, as well as enhancement of the renal parenchyma. The RBF, RVD, and MTT maps were calculated (not shown). Three slices were chosen from a set of 32 slices for each map. Mean RBF, RVD and MTT values were 192 ± 42 ml/100g/min, 22.1 ± 6.0 ml/100g, and 9.8 ± 6.6 sec in the cortex. The RBF and RVD values were underestimated, while MTT was overestimated compared to the values found in literature: RBF=380ml/100g/min,

RBV=27ml/100g, MTT=4.4min (6-7). To our knowledge, the technique

presented has been the first to combine both the time-resolved MRA and perfusion in a single sequence, which decreases acquisition time and amount of contrast agent injection. The main features of this technique that make this possible are: 1) high temporal resolution and number of

temporal samples from CAMERA and sliding window reconstruction and 2) 3D coverage of the renal parenchyma. Conclusion Although an in-depth comparison with a standard of reference (e.g. microspheres) is required to verify the measured perfusion parameters, this technique has successfully produced reasonable measurements found in literature while providing a time-resolved MRA. References 1) Jeong et al., MRM 2010 (In Press). 2) Cashen et al. MRM 2007. 3) Riederer et al. MRM 1988. 4) Dujardin et al. MRM 2005. 5) Rempp et al. Radiology 1994. 6) Aumann et al. MRM 2003. 7) Shoenberg et al. MRM 2003.


10.3 Non-Contrast MRA at 3T Mitsue Miyazaki, Yuichi Yamashita, Andrew Wheaton, Wayne Dannels, Masaaki Umeda,

Masao Yui, Hitoshi Kanazawa, Satoshi Sugiura Objective: Despite the recent advancements in 3T, non-contrast MRA faces many problems such as a specific absorption rate (SAR) and B1 inhomogeneity. At 3T, a common method to comply with SAR limitations is to reduce RF refocusing pulse flip angles. However, this approach makes it difficult to maintain bright blood signal necessary for MRA applications. In addition, the B1 wavelength effect caused by conventional quadrature RF transmission makes shading or nonuniform signal intensity unavoidable. This shading effect is problematic especially in the iliac area [1]. In this study, we have adjusted the pulse sequences to lower SAR and addressed the signal shading issue by applying multi-phase RF transmission. Materials and Methods: All studies were performed on healthy volunteers using a clinical unit (Vantage TitanTM Toshiba, Japan) and a research unit. Both half-Fourier FSE (FASE) and balanced SSFP (bSSFP) sequences were optimized in terms of RF refocusing pulses to lower the SAR. The non-contrast MRA studies were performed in abdomen and peripheral run-offs using time-spatial labeling inversion pulse (time-SLIP) [2] and fresh blood imaging (FBI) [3], respectively. Results: Renal MRA using time-SLIP shows better delineation of the renal branches. The longer T1 at 3T allows for a longer black blood inversion time (BBTI), thus enabling a longer duration for inflow into the renal branches while maintaining good background suppression. In the peripheral run-offs, the femoral and calf FBI images present high arterial signal intensity enabling better depiction of small branch arteries. In the iliac region, with application of multi-phase transmission, both the right and left femoral arteries in FBI images show uniform signal intensity without shading. Conclusion: At 3T, excellent non-contrast MRA images were obtained. The optimized FASE sequence generates high arterial signal intensity within SAR limitations. The longer T1 at 3T can be leveraged to increase inflow signal in combination with better background suppression in time-SLIP renal MRA. Multi-phase RF transmission sufficiently mitigates the B1-related signal shading issue for MRA. References: 1] Storey P, Lee VS, Sodickson DK, et al, ISMRM p425, 2009 2] Kanazawa H and Miyazaki M. ISMRM p140, 2002. 3] Miyazaki M, Takai H, Sugiura S, et al, Radiology 227:890-896, 2003.

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10.5 Evaluation of the renal arteries using two types of Non-contrast MRA: FIESTA with flow preparation pulse and

FIESTA with Inhance Inflow IR technique Takayuki Masui1, Motoyuki Katayama1, Kimihiko Sato1, Hiroki Ikuma1, Takuma Terauchi1,

Masayoshi Sugimura1, Naoyuki Takei2, Mitsuharu Miyoshi2, Tetsuji Tsukamoto2, Hiroyuki Kabasawa2

1) Seirei Hamamatsu General Hospital, Japan, 2) GE Healthcare Japan Introduction; Non-contrast (NC) MRAs with several techniques have been introduced such as 3D FIESTA combined with flow preparation pulse (Flow-Prep) based on bipolar velocity encoding to distinguish artery from vein and background and 3D FIESTA with Inherent enhancement (Inhance) inflow inversion recovery (IR) pulse. The purpose was to evaluate abilities of NC MRAs using Flow-Prep (Flow-prep MRA) and Inhance inflow IR (Inhance IR MRA) for demonstration of renal arteries in preoperative evaluations compared with dynamic contrast MRA (C MRA). Methods: Population: 31 consecutive patients (median age 60 years (40-77years)) underwent contrast enhanced MR imaging for the evaluation of the kidney and renal artery and were included. Pathologies were renal cancer in 10, pelvic tumor in 3, renal benign lesions in 7, adrenal tumor or cyst in 3, miscellaneous in 1, renal arterial stenosis in 2 and normal in 5. MR imaging: NC MRAs on a 1.5T magnet were obtained with two different methods: respiratory triggered ECG gated Flow-Prep 3D FIESTA (Flow-prep MRA) in coronal plane, respiratory triggered Inhance Inflow IR 3D FIESTA (Inhance IR MRA) in axial plane. For each, imaging time was 2.5 to 4 min. C MRA was obtained using 3D gradient echo sequence (EFGRE) with 0.1mmol/kg of gadolinium injection (0.3ml/sec) with smart prep (GE) in 24 seconds’ breath hold. Data analysis: Image quality, artifacts, and overlap of the renal artery and veins were ranked with 5 -point scale (1 bad to 5 excellent). Recognitions of aorta at upper (diaphragm to renal artery) and lower (renal to bifurcation) levels, renal arteries at five levels (proximal, middle, distal, 2nd, and 3rd order) were ranked with 5-point scale. Subjective evaluations were performed by two radiologists. Wilcoxon signed rank test was used for comparison. Results: In two of 31 patients, NC MRA was not diagnostic with in coronal Inhance IR and two with axial Inhance IR. In all, Flow-prep MRA and C MRA provided diagnostic information. Overall image quality and artifacts were not significantly different among MRAs, respectively (NCs:C=4.3-4.4: 4.5, P>0.05). The aorta from diaphragm to bifurcation was well recognized on Flow-prep MRA and C MRA (NC:C=4.9: 5, NS). Axial Inhance IR MRA provided limited information of coverage of the aorta but better recognition of the peripheral renal arteries (Peripheral Renal A; Axial Inhance: Flow prep: C MRA= 4.7:4.5:4.3). Proximal to mid renal arteries were equally detected on all MRAs (NCs:C=4.6: 4.6, NS). Overlaps of veins and soft tissues were less recognized on NC MRA than C MRA (NCs:C=4.3-4.7: 3.2-3.4, P<0.05). The recognition of the number of the renal arteries was equally made on C MRA and Flow-prep. Axial Inhance IR missed some of renal arteries which branched from lower part of the aorta. In all cases, renal stenosis was well recognized on all N MRAs and C MRA. Summary: With no risk of side effects related contrast agents, NC MRA clearly demonstrated vascular anatomy without overlaps. Flow-prep MRA covers wide range of the abdominal aorta and Inhance IR MRA provides better resolution of the distal renal arteries. For the preoperative evaluation of the renal arteries, anatomical information can be successfully obtained with combination of NC MRAs using Flow-Prep and Inhance flow IR pulse, respectively.


10.6 Improved signal in inflow-sensitive bSSFP MRA using variable flip angles

Pauline W Worters and Brian A Hargreaves Radiology, Stanford University, CA, USA

Purpose Inflow-sensitive techniques typically use a preparation module (comprising inversion and/or saturation pulses) to suppress background tissue signal while allowing time for arterial inflow to occur in order to generate contrast for MRA. Such methods usually require the acquisition to be broken or segmented, and thus the magnetization does not reach steady state. Here, more signal can be gained from the transient balanced SSFP (bSSFP) magnetization by using variable excitation flip angles. Theory We present a novel, simple algorithm (variable angles for uniform signal excitation, VUSE, previously coined in [1] for SPGR) to calculate a series of flip angles to produce a uniform echo amplitude profile for bSSFP, which can be used iteratively to maximize the overall signal of a target species. Methods All studies were performed using a 1.5T MRI scanner with IRB approval. A 3D bSSFP pulse sequence with Kaiser-filtered ramp (5 RF pulses) catalyzation (to minimize off-resonance artifacts from oscillations) [2] was modified to perform variable flip angle calculations on-the-fly. Two IR pulses were used to provide background and fat suppression (Figure 2). An 8-channel phased array coil was used. Common parameters between standard and VUSE bSSFP were: matrix = 256×77×50; FOV = 33×20 cm; slice thickness = 1.6 mm; TI = 1.1 s; with linear phase encode ordering, fat-selective IR and respiratory triggering. 77 phase encodes (i.e., one complete kz plane) were acquired per acquisition block. The TR was slightly higher in VUSE bSSFP (5.6 ms versus 4.6 ms) to accommodate the high flip angles. Results & Discussion VUSE angiograms have higher signal, and improved small vessel depiction (Figure 3), attributed to the higher echo amplitude at k-space center, and higher integral of the echo amplitude versus time curve. Fat suppression is poorer in VUSE, perhaps due to the increased TR resulting in sub-optimal fat nulling with the fat-selective IR, which can be mitigated by changing the phase encode acquisition ordering. VUSE bSSFP provides a method for increasing signal in a transient bSSFP imaging

acquisition. Other advantages from the uniform echo signal may include improved resolution and SNR efficiency. Limitations of VUSE include increased TR and B1 sensitivity due to the high flip angles used (Figure 1, inset), which can be avoided by simply limiting the maximum flip angle in the algorithm. The algorithm can also provide any arbitrary sequence of echo amplitudes such as ramped or windowed profiles that may improve other applications. Conclusion Modulating echo profiles by calculating a scheme of flip angles can improve signal in bSSFP transient imaging and improves small vessel depiction in inflow-sensitive angiography. References [1] Priatna A & Paschal CB. JMRI 5:421, 1995. [2] Le Roux P. JMR 163:23, 2003.

Figure 1: Using variable flip angles to avoid transient decay modulation and maximize bSSFP signal.

Figure 3: Axial MIP renal angiograms from inflow-sensitive bSSFP acquisitions using constant flip angles (60°) and VUSE. VUSE has higher signal and improved small vessel depiction (white arrows). The images are displayed at the same window and level.

Figure 2: Respiratory-triggered inflow-sensitive sequence used to acquire renal angiograms without contrast administration.


a. b. c. d.

e. f.

Figure1: Results from volunteer study #3. Consecutive frames from 2 ml timing bolus (a,b,c,d) and the subsequent high resolution renal MRA volume rendering (e) and targeted MIP (f).

10.7 High Temporal and Spatial Resolution Abdominal CE-MRA

P. M. Mostardi, J.F. Glockner, S. J. Riederer Department of Radiology, Mayo Clinic, Rochester, MN 55905 USA

Purpose In abdominal CE-MRA high spatial resolution is necessary for accurate diagnosis of renal artery stenosis and other vascular pathologies. Obtaining high spatial resolution and SNR images is particularly challenging in the abdomen due to limited scan time, a breath hold (~20 sec), and often the need to image over a large FOV. Furthermore, high frame rate time-resolved imaging may be desired in order to obtain temporal information useful for the understanding of abnormal flow and vascular filling patterns. The tradeoff of temporal and spatial resolution has changed with the introduction of parallel imaging techniques, but highly accelerated acquisitions have yet to be effectively applied to abdominal imaging. The purpose of this work is to develop a abdominal CE-MRA method that implements the CAPR sampling method and high SENSE accelerations in order to achieve high temporal and spatial resolution imaging of the abdominal vasculature using a single dose of contrast material. Methods Acquisition. An abdominal imaging protocol was developed that implements the CAPR pulse sequence and parallel imaging. CAPR is a Cartesian 3D acquisition method in which the kY-kZ plane is fully sampled in a central ellipse and asymmetrically undersampled in the periphery. When view-sharing is applied the periphery is divided into N vane sets, one of which is sampled each image update. The imaging protocol consists of a low-dose time-resolved CAPR scan (timing bolus) and a high resolution renal MRA. The timing bolus scan uses a small central k-space region and a view-share factor of 4. The high resolution scan samples a very large central ellipse region. For both, a 2D SENSE acceleration factor of 8 (RY = 4, RZ = 2) was applied. Reconstruction. The images are automatically reconstructed using custom hardware and sent back to the scanner console within two minutes of the completion of the scan, making it clinically feasible to use CAPR as a timing bolus. Receiver Coil. A circumferential modular coil array with 8-16 elements has been developed for accelerated abdominal imaging. The modular nature of the array readily allows the number of elements used to be determined by volunteer size; 10 elements was generally the appropriate number. In Vivo Studies. Six volunteer studies have been performed. In these studies the sampling parameters for the time-resolved CAPR acquisition were FOV 35-40 x 35-40 x 25.6-28 cm3, spatial resolution 1.37-1.56 x 2.19-2.50 x 2.0-2.20 mm3, view-share factor 4, 8x (4 x 2) SENSE acceleration, frame time 1.41 sec. The high resolution renal MRA is a single phase CAPR acquisition with FOV 35-40 x 35-40 x 25.6-28 cm3, spatial resolution 1.37-1.56 x 1.09-1.25 x 1.0-1.1 mm3, 8x (4 x 2) SENSE acceleration, acquisition time 24 sec. The FOV was modified on a volunteer specific basis such that the entire central abdomen was included within the FOV. All scans were performed with during end-expiration breath hold. The injection protocol for the low-dose time-resolved exam consisted of 2 ml Multihance at 3 ml/sec followed by 20 ml saline at 3 ml/sec. For the high resolution scan the remaining 18 ml of Multihance was injected at 3 ml/sec followed by 20 ml saline at 3 ml/sec. Results In all six studies the transit of the test bolus through the abdominal vasculature was well seen. All six single phase angiograms portrayed the abdominal arterial vasculature well. Representative results are shown in Fig. 1. Fig. 1 (a,b,c,d) show four 1.4 sec consecutive time frames from a time-resolved CAPR scan depicting the arrival of the contrast bolus to the abdominal aorta and progressive filling of the vasculature. This scan provides dynamic information, an overview of the vasculature, and serves as a timing scan. Fig. 1(e) volume rendered and (f) targeted MIP images from the subsequent high spatial resolution renal angiogram show excellent depiction of the renal arteries, splenic artery and mesenteric vessels. Conclusion In a single contrast agent dose, both a time-resolved acquisition and a high resolution renal MRA were obtained by implementing variations of the CAPR sequence with high SENSE accelerations and specific purpose multi-element surface coil arrays. The low-dose time-resolved CAPR acquisition provides dynamic information and an overview of the vasculature as well as serves as an accurate timing scan for the renal MRA. This work suggests that high quality MR angiograms of the renal and other abdominal vasculature can be obtained with highly accelerated acquisition techniques.

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10.9 Rapid Angiography and Perfusion with Multi-Echo 3D Radials and an Echo Weighted Constrained Reconstruction

Kevin M. Johnson1, Ethan Brodsky1, Alexey Samsonov1-2, Walter Block1-3, Oliver Wieben1-2, Scott B Reeder1-3

Department of Medical Physics1, Radiology2, and Biomedical Engineering3, University of Wisconsin-Madison, Madison, USA

Purpose: MR Angiography and perfusion techniques suffer from limited resolution due to limited acquisition windows. Multi-echo non-Cartesian trajectories can increase acquisition efficiency; however inconsistencies between the echoes and undersampling artifacts degrade image quality. In this work, we investigated a synergistic combination of echo weighted parallel imaging, multi-echo 3D radial trajectories, and constrained reconstruction for improved image quality at high acceleration factors. Methods: We have developed and previously reported a 3D radial 4-half echo trajectory

[1] that samples 4 distinct lines in k-space within a single TR. To incorporate parallel imaging while reducing artifacts from k-space data inconsistencies, images are reconstructed by minimizing the function: where is the encoding matrix with coil sensitivities, is the image, is the raw data, and is any desired regularization. is a weighting function that weights data as a function of readout time, favoring solutions at a particular echo time. Weighting balances noise amplification from parallel imaging with imaging artifacts from multiple echoes. As a representative example, whole abdomen liver perfusion images were acquired with a real-time guided 3D radial sequence using 20 receiver channels [2]. Images were reconstructed with a true temporal footprint of 4s and a spatial resolution of 2mm isotropic with gridding and the proposed reconstruction. The only regularization utilized was a term that penalized the imaginary component of the signal: ; which enforces hermitian symmetry in k-space [3]. Results: Example images obtained from both reconstructions are shown in Fig 1. Images reconstructed with the echo weighted iterative reconstruction show improved SNR and reduced undersampling artifacts. Additionally, artifacts arising from data inconsistencies, such as off resonance at the lung interface, are greatly reduced using the echo weighted reconstruction. Conclusion: The proposed acquisition/reconstruction scheme shows excellent image quality at high acceleration and is widely applicable to a variety of angiographic sequences with flexibility to utilize compressed sensing and constrained reconstruction techniques. References: 1. Lu et al. MRM 53:692-699 (05’) 2. Brodsky et al. ISMRM 10’ #2618 3. Bydder at al. MRM 53:1393-1401 (05’)

Figure 1. Example 4s limited MIPs showing improvedimage quality with iterative reconstruction. Arrows pointshow reduced artifacts at the lung interface.


11.1 3D Visualization of the lenticulostriate artery and the correlated infarct

Chan-A Park1, Chang-Ki Kang1, Stefan Wörz2, Karl Rohr2, Young-Bo Kim1, Zang-Hee Cho1

1. Neuroscience Research Institute, Gachon University of Medicine and Science, Korea 2. Department of Bioinformatics and Functional Genomics, University of Heidelberg,

BIOQUANT, IPMB, and German Cancer Research Center (DKFZ), Germany PURPOSE: Small vessel diseases have been studied with MRI non-invasively, but a direct detection or visualization of the micro vessels related to the small infarct has not been eased 1-2. Hence, one could presume that the vessels might be occluded or abnormal narrowing. We assumed that high field MRA could be utilized to directly identify the micro vessel from which the infarct originated. The present study is to investigate the affected micro vessels with its corresponding infarct with a model for three dimension visualization. METHODS: We have detected the lenticulostriate artery in patients, who have suffered strokes in the basal ganglia, causing to the micro infarct using time of flight MRA at ultra high field (7T) MRI, modeled them through three dimension vessel segmentation 3, and visualized the infarct and the correlated vessel together. We also compared the vessels of our selected patients with those of other typical patients as well as age-matched healthy subjects. RESULTS: The results showed that the typical stroke patients had the degradation of small vessels, compared to the particular patients as well as healthy subjects. The particular patients had only one vessel degraded, which was closely located on the side of the infarct. CONCLUSION: This study provides that 7T MRI could detect the vessel related to the small infarct and the 3D vessel modeling visualize obviously the abnormality of the micro vessel. The direct visualization of the affected micro vessels observed non-invasively, together with the development of sensitive MRI techniques for detecting them, will provide critical information toward the advancement of detecting small vessel diseases, diagnosing and treating the patient 4. REFERENCES: 1. Cho ZH, et. al., Stroke 2008:1604 2. Kang CK, et. al., MRM 2009:136 3. Wörz S, et. al., IEEE Trans 2007:1994 4. Greenberg SM. N Engl J Med 2006:1451


11.2 High Resolution 2D Radial FLASH MR DSA for Intracranial Vascular Disease

P. Vakil1, M. Hurley2, H. Batjer2, B. Bendok2, C. Eddleman2, T. Carroll1,3

1Biomedical Engineering, Northwestern University, Chicago, IL 2Northwestern Memorial Hospital 3Radiology, Northwestern University

Introduction: 2D MR DSA, also known as MR projection angiography, has demonstrated clinical feasibility as a diagnostic, decision-making, and surgical-planning tool. By eliminating the need for slice encoding, 2D MR DSA is capable of providing sub-millimeter spatial resolution at frame rates of 1 frame/s (1). Recently, sliding window view sharing (2) has been applied to 3D CE MRA to increase apparent frame rate (3-5). While an improvement, the spatial (~1.0 mm in-plane) and temporal (> 1 fps) resolution is still an order of magnitude behind X-ray DSA (0.2mm in-plane resolution, frame rate 6-24 frames/s). We have applied pseudorandom, radial sampling and view-sharing to 2D MR DSA for the purpose of imaging intracranial vascular disease. Initial images had concentric circular banding artifacts. We propose a new approach to magnetization spoiling in 2D FLASH protocols to eliminate these artifacts.

Materials and Methods: We developed a 2D MR DSA pulse sequence based on a previously reported 3D CE MRA protocol (6) utilizing a radial FLASH acquisition with pseudorandom view ordering and sliding window reconstruction. This new pulse sequence is capable of acquiring 0.57 mm isotropic, in-plane spatial resolution projection

angiograms at 10 frames/s. Spoiling. Spoiling transverse coherences in FLASH is

achieved by varying the phase shift spins experience at each position between TR intervals (7). This can be induced through the use of RF-phase cycling or the application of time-varying gradients. The latter have been shown to produce parallel banding artifacts due to a positional dependence on between subsequent TR intervals (7-8). In 2D radial FLASH, this is manifested as concentric rings. We conducted Bloch Equation simulations and phantom studies to predict, explain, and quantify the appearance of artifacts associated with different radial acquisition strategies. Our results were used to develop the following spoiling strategy to eliminate these artifacts. In a standard radial trajectory, imaging gradients are given by and ,

where , the radial projection angle, varies such that for n=0,…,N-1 radial views. We propose a scheme in which spoiler magnitude is a function of projection angle. That is

spoilers Gs,x and Gs,y will be calculated as and . Intracranial MRA. With IRB approval, we applied our modified 2D MR DSA pulse sequence (TR/TE=6.12 ms/1.86 ms, θ=30°, BW=651 Hz/pixel, Matrix=384, Nproj=384, FOV=220 mm to visualize the hemodynamics of the intracranial vasculature. The raw data was acquired using a standard 3T (Trio, Siemens) with a single dose contrast injection (Magnevist) Results/Discussion: Our simulation and phantom studies predicted that a radial sampling trajectory in 2D FLASH sequences will produce spatial inhomogeneities in spoiled transverse magnetization due to

spatially dependent resulting in the image artifacts shown in Fig. 1a-b (arrows). These are eliminated (Fig. 1c-d) with a modified spoiling strategy that balances gradient moments along each physical axis (Fig. 2). Figure 3 shows a single frame of a time-series 2D MR DSA acquisition of intracranial vasculature in a human volunteer at 0.57 mm resolution. Ring artifacts are not present and small vessels are resolved. This new insight into the nature of artifacts in radial FLASH sequences may also find application in truly 3D radial FLASH-based VIPR pulse sequences. References 1) Hennig et al., MRM 1997. 2) Riederer et al., JMRI 1997. 3) Korosec et al., MRM 1996. 4) Eddleman et al., Stroke 2009. 5) Jeong et al., MRM 2009 6) Cashen et al., MRM 2007. 7) Zur et al., MRM 1991. 8) Crawley et al., MRM 1988


11.3 Nonenhanced ECG-gated time-resolved 4D Steady-State Free Precession MR Angiography (4D SSFP MRA) in

assessment of intracranial collateral flow: comparison with digital subtraction angiography (DSA).

Lanzman RS1, Kröpil P1, Schmitt P2, Bi X3, Miese FR1, Hänngi D4, Turowski B1, Scherer A1, Blondin D1

1Department of Radiology, University Hospital Düsseldorf, Germany 2Siemens AG, Healtcare Sector, Erlangen, Germany

3Siemens Medical Solutions USA, Inc., Chicago, IL, USA 4Department of Neurosurgery, University Hospital Düsseldorf, Germany

Purpose: In patients with significant stenosis or occlusion of brain-supplying arteries, the circle of Willis is the primary collateral pathway to maintain cerebral perfusion. Conventional digital subtraction angiography is considered as the goldstandard for assessment of the intracranial circulation, but exposes the patients to ionizing radiation and potential procedural risks, as thromboembolic complications. Therefore, the purpose of this study was to evaluate a novel nonenhanced ECG-gated time-resolved 4D Steady-State Free Precession MR Angiography (4D SSFP MRA) [1] for dynamic visualization of intracranial collateral blood flow. Methods: 18 patients (58.4±12.4 years) with stenooclusive disease of brain-supplying arteries were included in this study. 4D SSFP MRA of the intracranial arteries was acquired with 15 temporal phases, a temporal resolution of 115 ms and a spatial resolution of 1.2x1.0x1.0 mm on a 1.5T MR scanner (Magnetom Avanto, Siemens AG, Healthcare Sector, Erlangen, Germany). ECG-gated image acquisition was performed with increasing trigger times following spatially selective and non-selective inversion (FAIR technique) to obtain time-resolved images. Acquisition time ranged between 4 and 6 min. Cerebral DSA served as a reference standard and was available in all patients. Results: With 4D SSFP MRA, dynamic visualization of blood flow in the circle of Willis and its branches was successful in 17 of 18 (94.4%) patients. Collateral flow was excluded with both 4D SSFP MRA and DSA in 4 patients. In 13 patients, including 6 patients with an extracranial-intracranial (EC/IC) bypass, DSA disclosed collateral flow via the anterior communicating artery (n=7), the posterior communicating artery (n=11) and a patent EC/IC bypass (n=8)(Figure 1). In accordance with DSA, 4D SSFP MRA disclosed retrograde filling of the basilar artery in two patients and markedly reduced flow in the right ICA and MCA without collateral supply in one patient. Collateral flow via the posterior communicating artery (n=1) and an EC/IC bypass (n=1) were missed with 4D SSFP MRA in one patient each. As compared to DSA, 4D SSFP MRA showed a high sensitivity (92.3%), specificity (100%) and accuracy (93.3%) for dynamic visualization of collateral flow. Conclusion: 4D SSFP MRA is a novel promising technique for nonenhanced dynamic visualization of cerebral arteries. As a nonenhanced imaging technique it can be applied safely in patients with contraindications for contrast material, as for example renal insufficiency. References: Bi X, Weale P, Schmitt P, Zuehlsdorff S, Jerecic R. Non-Contrast-Enhanced Four-Dimensional (4D) Intracranial MR Angiography: A Feasibility Study. MRM 2010; 63: 835-841.

Figure 1: Patient with an occlusion of the right ICA. Collateral flow via the anterior and posterior communicating artery is visualized with 4D SSFP MRA and was confirmed with DSA.


11.4 High-spatial resolution time-resolved 4D MR angiography of cerebral arteriovenous malformations:

experience in 50 patients using different MRA protocols and different contrast agents

Hadizadeh DR1, Kukuk GM1, Gieseke J1, Tschampa H1, Kovács A1, Greschus S1, Urbach H1, Bostroem A2, Schild HH1, Willinek WA1

1University of Bonn, Dept. of Radiology; 2University of Bonn, Dept. of Neurosurgery Purpose: To compare contrast-enhanced 4-dimensional MR angiography (4DMRA) with high spatial and temporal resolution and digital subtraction angiography (DSA) in 50 patients with cerebral arteriovenous malformations and to analyze the impact of sequence modifications and change of contrast agent application. Methods: 50 consecutive patients with cAVM (26 women, 24 men; age: 38.9 ±13.4 (18–69) years) were examined on a 3.0 Tesla whole body MR system (Philips Healthcare, Best, the Netherlands) and received both 4DMRA (1) and DSA examinations. 20/50 (40%) patients who were operated received both 4DMRA and DSA pre- and postoperatively. Contrast-enhanced 4DMRA was performed using keyhole (2,3), CENTRA (4), partial Fourier, and parallel imaging (5) in 19/50 patients (group 1; standard protocol). In 31/51 patients (group 2) alternating view-sharing was additionally implemented (6). Group 1 received 4DMRA with a spatial resolution of (1.1 x 1.1 x 1.4 mm³) and a temporal resolution of 608 ms/ dynamic frame after application of 0.5 M Gd-DTPA (Magnevist, Bayer Schering Pharma). Group 2 received 4DMRA with a spatial resolution of (1.1 x 1.1 x 1.1 mm³) and a temporal resolution of 572 ms/ dynamic frame after application of 1.0 M gadobutrol at equimolar dosage compared to group 1 (Gadovist, Bayer Schering Pharma); 4DMRA and DSA images were independently reviewed by two readers with respect to Spetzler-Martin classification (7), arterial feeders and operative resection of the cAVM. Results: In 50/50 patients Spetzler-Martin-classification of cAVM as determined by 4DMRA matched for both readers with DSA results (fig.1, Spetzler-Martin-Grades, I: 10, II: 22, III: 14, IV: 3, V: 1). 82/89 (92.2%) arterial feeders were identified by 4DMRA and were confirmed by DSA. 7 additional arterial feeders were identified by DSA only. In group 1, additional arterial feeders were found by DSA in 3/19 (15.8%) patients and in group 2, additional feeders were found by DSA in 4/31 (12.9%) patients. The evaluation of residual cAVM filling by 4DMRA and DSA matched in 20/20 patients: residual filling was excluded and complete resection of the cAVM was confirmed in postoperative 4DMRA accordingly to DSA in 19/20 (95%) patients. Residual post-operative filling of cAVM was diagnosed in 1/20 (5%) patients and was confirmed intraoperatively. Conclusion: 4DMRA matched with DSA in all patients regarding pre-operative Spetzler-Martin-classification and postoperative assessment of residual filling of cAVM and may be considered a non-invasive alternative in the entire diagnostic work-up of patients with cAVM. 4DMRA with additional view-sharing and 1.0 M gadobutrol performed slightly better as compared to the standard protocol. References (1) Willinek WA, Hadizadeh DR, von Falkenhausen M, et al. 4D time-resolved MR angiography with keyhole (4D-TRAK):

more than 60 times accelerated MRA using a combination of CENTRA, keyhole, and SENSE at 3.0T. J Magn Reson Imaging 2008; 27:1455-1460.

(2) Jones RA, Haraldseth O, Muller TB, Rinck PA, Oksendal AN. K-space substitution: a novel dynamic imaging technique. Magn Reson Med 1993; 29:830-834.

(3) van Vaals JJ, Brummer ME, Dixon WT, et al. "Keyhole" method for accelerating imaging of contrast agent uptake. J Magn Reson Imaging 1993; 3:671-675.

(4) Willinek WA, Gieseke J, Conrad R, et al. Randomly segmented central k-space ordering in high-spatial-resolution contrast-enhanced MR angiography of the supraaortic arteries: initial experience. Radiology 2002; 225:583-588.

(5) Pruessmann KP, Weiger M, Scheidegger MB, Boesiger P. SENSE: sensitivity encoding for fast MRI. Magn Reson Med 1999; 42:952-962.

(6) Hadizadeh DR, Gieseke J, Beck G, Geerts L, Kukuk GM, Boström A, Urbach H, Schild HH, Willinek WA. View-sharing in keyhole imaging: Partially compressed central k-space acquisition in time-resolved MRA at 3.0T. Eur J Radiol. 2010 May 4. [Epub ahead of print]

(7) Spetzler RF, Martin NA. A proposed grading system for arteriovenous malformations. J Neurosurg 1986; 65:476-483.


11.5 High Resolution Vessel Wall MRI of the Chronic Unilateral Middle Cerebral Artery Occlusion

Chang-Woo Ryu, MD1; Geon-Ho Jahng, PhD1; Eui-Jong Kim, MD2; Woo-Suk Choi, MD2 1Department of Radiology, Kyung Hee East-West Neo Medical Center, School of Medicine,

Kyung Hee University, Seoul, Korea 2Department of Radiology, Kyung Hee University Hospital, School of Medicine, Kyung Hee

University, Seoul, Korea Background: The characterization of the morphology of an occluded segment may help evaluate the etiology of the chronic intracranial artery occlusion. We acquired the high-resolution vessel wall MRI of middle cerebral artery (MCA) in patients with chronic unilateral MCA occlusion and evaluated the characteristics of MRI and clinical findings. Materials: We selected 20 consecutive patients (M:F = 10: 10; mean age = 63.7 years) who presented with unilateral MCA occlusion as documented by MR angiography. High-resolution proton-density weighted TSE MRI with the saturation of inflowing arterial blood was acquired of the occluded MCA using 3.0 tesla MRI. We surveyed the morphology of the MCA at the occluded segment. Symptoms, the presence of other stenotic arteries and atherosclerosis risk factors were compared for patients grouped by different finding on high-resolution vessel wall MRI. Results: MCA occlusion was classified as plugged MCA (15/20) with a clear view of MCA or atrophic MCA group (5/20) with no MCA trunk visible in the sylvian fissure. The presence of other stenotic arteries (73.3% vs. 0%) and atherosclerosis risk factors (86.7% vs. 40 %) were more frequent in plugged MCA group than in atrophic MCA group. Conclusions: plugged MCA could be caused by atherosclerosis, but atrophic MCA could be by non-atherosclerotic etiology. When a patient has complex risk factors for multiple diseases or insufficient risk factors for atherosclerosis, morphological analysis by using vessel wall MRI may help evaluate the etiology of the disease.


11.6 Effectiveness of Fat-Suppression MRAngiography Comparing with Standard 3D-TOF MRA in Revealing

Cerebrovascular Diseases. Keiji Igase, Ichiro Matsubara, Masamori Arai, Jyunji Goishi, Kazuhiko Sadamoto

Department of Neurosurgery, Washokai Sadamoto Hospital

Purpose 3T MRI has superior S/N ratio and frequency resolution, which enabled main cerebral arteries to be more clearly delineated, comparing with low-tesla MRI. In our hospital 3T MRI was introduced for clinical use in 2006 and by adding further version-up the new sequence of fat-suppression MRAngiography (MRA) has been put into place since summer 2009. Therefore, we have scrutinized the effectiveness of fat-suppression MRAngiography in comparison with standard 3D-TOF MRA. Methods Out of 286 unruptured cerebral Aneurysms (ANs) pointed out with 3T MRI in 2006, 10 cases that underwent a followed-up MRI including fat-suppression MRA had been enrolled. MRI system in the initial case was SIGNA Excite (GE healthcare: USA), meanwhile in the 2nd case SIGNA HDxt was applied for fat-suppression MRA. As regards the assessment of delineation ability on both standard 3D-TOF and fat-suppression MRA, educated 2 neurosurgeons and 1 radiologist rated on 0 to 2 depending on their clearness using both MIP (Minimum Intensity Projection) and VR (Volume Rendering) image individually with no information about each bilateral ophthalmic, middle cerebral arteries, and ANs. Results Rates of both bilateral ophthalmic arteries and ANs on fat-suppression MRA were significantly higher than those on standard 3D-TOF (p<0.05), on the other hand as for both bilateral middle cerebral arteries there were not any significant difference between two sequences. Conclusion Fat-suppression MRA could more precisely delineate intracranial narrow arteries like ophthalmic ones comparing with standard MRA, moreover regarding ANs their visualization was ameliorated by fat-suppression MRA. Accordingly this brand-new MRA sequence should be beneficial for a diagnosis of many cerebrovascular diseases.


11.7 3-Tesla VR Images of Brain Tumor: Pre-surgical planning

Hitoshi Miki1, S. Oda1, K. Kikuchi1, S. Ohue2, T. Mochizuki1, Department of Radiology1 and Neurosurgery2 , Ehime University School of Medicine,

JAPAN

Purpose: To evaluate the usefulness of 3T volume rendering (VR) images of brain surface and venous structure for pre-surgical planning in patients with glioma. Methods: Ten patients with glioma were examined by 3T MRI with/without Gd-DTPA. 3D turbo T1-FFE (3D T1-TFE) sequences was performed with a reconstruction matrix of 512(a scan matrix of 288), a slab of 180(0.75x240) mm, TR/TE/FA (15/3.45/10), and SENSE factor (1.8). VR images were generated on a workstation. In addition, the utility of the VR images as the pre-surgical planning was evaluated by comparing with surgical findings. Results: 3T VR with enhanced 3D T1-TFE sequence was able to offer brain parenchyma, tumor and venous structure in a good contrast for generating the 3D images. The resulting 3T VR method depicted brain surface, brain tumor and superficial venous structure, as well as important landmarks of brain surface anatomy. The 3D images generated by our procedure, never contained spatial misregistration between the 3D objects, because the 3D objects were generated from the same single MR data. 3T VR images were enable to demonstrate accurately the relations between brain surface, tumor and venous structure from voluntary direction, and made easily understood. 3T VR images were very helpful for determination of surgical approach, and well correlated with surgical findings. Conclusion: 3T VR image images are very useful and essential for the pre-surgical evaluation of brain tumor.


12.1 Supra-aortic Vascular Pathologies on Low Dose Time-Resolved CEMRA

Bum-soo Kim, Jee Hyun Seok, So-Lyung Jung, Kook-Jin Ahn Department of Radiology, Seoul St.Mary’s Hospital,

The Catholic University of Korea

3D time-resolved contrast enhanced MR angiography (TR-CEMRA) offers combined anatomic and hemodynamic information. In this talk, we present pictorial review of initial results using the low dose supraortic TR-CEMRA performed as routine protocol in addition to single phase high-resolution CEMRA (HR-CEMRA).

During 12 months since July 2009 to June 2010, over 800 cases of low dose TR-CEMRA had been performed at 3T. TR-CEMRA using TWIST and GRAPPA was performed after intravenous injection of gadobutrol at a constant dose of 2 cc bolus, at a flow rate of 1 cc/sec followed by a 20cc of saline flush at the same rate. Imaging parameters were as follows: TR 2.57ms; TE 0.97ms; flip angle 19°; rFOV 420x341; matrix 448x318 36 partitions; voxel size after zero interpolation 1.3 x 0.9 x 1.6 mm3 (true voxel size 1.3 x 0.9 x 1.6 mm3); GRAPPA with acceleration factor 3. Values of A = 8% and B = 20% of TWIST sequence were used for TR-CEMRA in our series. This imaging protocol provided a temporal resolution of 2.2 seconds with 7.8 sec of the temporal footprint. A total of 29 measurements were acquired.

In addition to the anatomical and morphologic information provided by the single-phase HR-CEMRA, low dose TR-CEMRA was clinically useful to give hemodynamic information in the patients with extracranial and intracranial stenoocclusive disease, intracranial vascular malformation with or without arteriovenous shunt, facial vascular malformation and tumors. TR-CEMRA could also be used as test bolus function to determine the maximal concentration of contrast at vessel of interest.

In summary, TR-CEMRA with TWIST and GRAPPA, using injection 2cc of Gadobutrol is feasible, and gives added hemodynamic information to the HR-CEMRA in patients with variable supraaortic vascular pathologies.


12.2 CINE Turbo Spin Echo Imaging Jason Mendes, M.Sc., Dennis L. Parker, Ph.D. and Jordan Hulet

INTRODUCTION Turbo Spin Echo (TSE) sequences acquire data over multiple repetition intervals. Each segment of data will therefore be acquired at different phases of the cardiac cycle causing image blurring or motion artifact. Gating the TSE images can be unreliable and can increase scan time significantly. Alternatively, several averages can be acquired with the hope of minimizing these artifacts. We propose a method to correlate data obtained from a non-gated TSE sequence to a patient’s physiological data. The result is a temporal series of images, each with reduced blurring and motion artifact. THEORY Information about the patient’s cardiac cycle is recorded during the MRI scan utilizing a pulse ox meter. The start time of each systolic period is determined and the acquired k-space lines are sorted into Nt bins according to the time elapsed since the last systolic trigger. The result is Nt undersampled data bins, each representing a different phase of the cardiac cycle. The undersampled images are reconstructed by simultaneously considering information encoded by the coil sensitivities and applying a temporal constraint. This is accomplished by minimizing the following objective function: ( ) ( ) ( )[ ] ( ) ( ) ( )[ ] 2

2t2

2yxnnxyyx t,y,xmy,xt,k,kdt,y,xmy,xst,k,kWG ∇⋅+−⋅ℑ⋅= λ [1]

where m(x,y,t) is our desired image, W(kx,ky,t) is a weight function specifying which k-space lines are acquired in each bin, ℑxy() is the 2D Fourier transform along the spatial coordinates, sn(x,y) is the coil sensitivity of the nth coil, dn(kx,ky,t) is the actual data acquired from the nth coil, λ(x,y) specifies the level of temporal constraint and ∇t() is a temporal gradient defined as:

( )[ ] ( )[ ]⎭⎬⎫

⎩⎨⎧

⋅ℑℑ=∇ −

tttt N

iTtyxmtyxm π2,,,, 1 [2]

Equation [1] is minimized using a non-linear conjugate gradient descent algorithm with back tracking line search and the following gradient of the objective function:

( )[ ] ( )[ ]{ }∑ −ℑ⋅ℑ+∇∇−=∇ ∗−∗∗

nnnxyxynttm dmsWWsmG 122 λλ [3]

METHOD AND RESULTS All data sets were obtained on a Siemens Trio 3T MRI scanner with a modified Turbo Spin Echo sequence. A variable density TSE sequence was used to help ensure adequate sampling of the center of k-space. DISCUSSION AND CONCLUSION From the images in Figure 1, one can clearly see the dynamics of the TSE images missed when simple signal averaging is used. In Figure 2, a measure of lumen diameter would be incorrect due to flow artifact in the averaged image (Fig. 2a) while the selected CINE image (Fig. 2b) more accurately depicts the vessel wall. Since the method was applied retrospectively the only increase in scan time is due to signal averaging, which is typically done anyway. We have shown the CINE TSE method to be a feasible alternative to cardiac gating.

Figure 2: The image formed from three averages is shown in (a) with a selected CINE image shown in (b).

b

a

Figure 1: 2D TSE images binned into 8 cardiac phases. Three signal averages were obtained from a custom 4 channel receive coil. The images have a 0.6x0.6x2mm resolution. The letters on each image correspond to the labeled pressure waveform to the right.

a b c d

e f g h

a

bd

ef

hg

c


12.4 Sex Differences of High-Risk Carotid Atherosclerotic Plaque Along with Different Levels of Stenosis – in vivo 3.0T

MRI study Hideki Ota1,2, Mathew J. Reeves1, David C. Zhu1, Michael J. Potchen1, Arshad Majid1,

Alonso Collar, FACS3, Chun Yuan4, J. Kevin DeMarco1. 1Michigan State Univ, East Lansing, MI. 2 Tohoku Univ, Sendai, Japan.

3Ingham Cardiothoracic & Vascular Surgeons, Lansing, MI. 4Univ of Washington, Seattle, WA

Purpose: To evaluate prevalence of carotid plaque characteristics, especially focusing on complicated, high-risk plaque between men and women along with different degrees of stenosis. Methods: Asymptomatic 139 patients (men, 67, women, 65) with ≥50% stenosis at least one carotid underwent bilateral carotid MRI scans with 3D TOF, T1WI, T2WI, 3D inversion recovery fast spoiled gradient recalled, CE-T1Wl and CE-MR angiography. Subjects’ demographic data (sex, age, hyperlipidemia, hypertension, coronary artery disease, peripheral vascular disease, diabetes mellitus, statin use and smoking) were collected. Arteries with poor image quality (12), prior CEA (20) and occlusion (16) were excluded. Presence of complicated American Heart Association type VI plaque, lipid-rich necrotic core (LRNC), thin/ruptured fibrous cap (FC), hemorrhage, calcification as well as MRA degree of stenosis were documented. Logistic regression models with generalized estimating equations were fit to determine the association of sexes and MRA degree of stenosis with plaque features, adjusted for subjects’ demographic data. Results: A total of 230 arteries (117 men, 113 women) were analyzed. Male sex and MRA degree of stenosis were independently associated with presence of AHA type IV, LRNC, thin/ruptured FC and hemorrhage (Table). Calcification was not significantly associated with sexes. Conclusion: Male sex and higher degree of MRA stenosis were both significantly associated with high-risk plaque. The present results indicate that mechanisms beyond the development of atherosclerosis appear different between male and female.

Associations among sex, stenosis and plaque features.

Sex* MRA stenosis†

aOR 95% CI p aOR 95% CI p

AHA type IV 4.1 2.1-8.0 <0.001 1.2 1.1-1.3 0.004

LRNC 3.6 1.9-6.8 <0.001 1.2 1.1-1.3 <0.001

Thin/ruptured FC 4.9 2.4-10.1 <0.001 1.3 1.1-1.5 <0.001

Hemorrhage 2.9 1.4-6.1 0.003 1.2 1.0-1.3 0.011

Calcification 1.2 0.6-2.6 0.579 1.2 1.1-1.5 0.005 *aOR for male vs. female; †aOR for 10% increase,


12.5 Quantitative Measurement of MR Constants in Carotid Plaque at 3T

Rui Li1,2, Jie Sun2, Marina S. Ferguson2, and Chun Yuan1,2 1. Center for Imaging Science and Technology, Tsinghua University, Beijing, China

2. Radiology Department, University of Washington, Seattle, Washington, United States Propose: Multi-contrast vessel wall imaging sequences have shown the ability to distinguish different components in carotid plaque. All these sequences only measure the weightings of basic MRI parameters such as T1, T2 and proton density, so the intensity of each image contrast relies on more than one parameter. Although Toussaint et al investigated the micro dissected components of plaques to determine water relaxation constants (T1 and T2) by NMR experiments and other researchers measured T2 mapping of ex vivo specimens using FSE imaging sequence, their studies are incomplete either in MR constant type (such as T2*) or in plaque components (such as hemorrhage). Our study aims to measure T1, T2 and T2* maps of 4 different components in ex vivo plaques on a 3T clinical system. Methods: Eight carotid endarterectomy specimens were imaged on a 3T MR scanner (Philips Achieva) after formalin fixation. Saturation recovery spin echo sequences with various delay times (TDs) instead of traditional inversion recovery were applied for T1 mapping because of their shorter TR and none phase aliasing. T1 map were calculated by Levenberg–Marquardt nonlinear fitting algorithm with acquired images. Spin echo and gradient echo sequences with different TEs were used to calculate T2 and T2* map by least square linear fitting algorithm after logarithmic simplification. Matched histology slices were stained using hematoxylin and eosin (H&E). An experienced reviewer outlined fibrous cap (FC), loose matrix (LM), lipid rich necrotic core (LRNC), and intra-plaque hemorrhage (IPH) regions on MR images guided by histology. Averages and standard deviations of mean values in these regions were calculated for different components. Results: The mapping results are shown in figure 1. Images (a), (b) and (c) are T1 map, T2 map and T2* map after nonlinear and linear fitting. T1 map of the formalin solution shows a lot of noise because the longest TD used for T1 mapping is not enough for measuring much longer T1 value of formalin solution. Calcification was not calculated because of its weak signal, and its area in T2* map is larger than T1 and T2 map as a result of susceptibility artifact. Intraplaque hemorrhage (e) (arrow) results in a relatively shorter T1, T2 and T2* than the surrounding fibrous tissue. Three MR constant maps were combined into a RGB image shown in (d). Contours used to calculate the average and standard deviation of MR constants are illustrated in (f), and the results are listed in table 2. Not surprisingly, LM has longest T1, T2 and T2* because of plenty of water in it. IPH indicated by the arrow in figure 1 results in shortest T1, T2 and T2* because of iron rich hemosiderin deposition. The MR constants distribution of LRNC overlaps with that of FC, which supports previous conclusion that it is hard to distinguish LRNC and FC without contrast agent. The T1 standard deviation of the LRNC is large due to the influence of cholesterol clefts (decrease signal) and cell debris (increases signal). T1 and T2 of LRNC are longer than that of FC, while it is reversed for T2* also because of the mixture components in LRNC. Conclusion: This study gives accurate information about MR constants which can be used to understand and optimize current multi contrast sequences.

Table 2. MR constants of different plaque components Components T1 (ms) T2(ms) T2*(ms) FC (n=14) 558.6±116.9 29.9±3.6 25.7±4.3LM (n=13) 1074.7±191.7 42.8±4.9 28.7±5.6LRNC (n=21) 815.8±278.2 34.3±4.3 18.7±2.4IPH (n=2)* 123.6±71.5 15.7±4.2 8.4±3.1 * It is an ongoing study. More IPH should be validated

(a) (b) (c)

Figure 1. Quantitative mapping (a) T1 map; (b) T2 map; (c) T2* map; (d) Combined RGB map; (e) Corresponding histology; (f) Contours drawn by an experienced reviewer

(d) (e) (f)


12.6 Atherosclerotic Plaque Imaging with SWI Approach Jie Zheng, Alexandros Flaris, David Muccigrosso, Adil Bashir.

Washington University, MO, USA Purpose: Multicontrast Plaque imaging approach with multiple scans was established to delineate various plaque components (lipid, calcification, intraplaque hemorrhage or IH). However, interscan motion, partial volume effect, and flow artifacts may render difficulty in the accurate segmentation of plaque components. The objective of this study is to explore susceptibility-weighted imaging (SWI) approach to identify plaque components in an effort to reduce scan numbers. Methods: In this pilot study, ex vivo MRI were performed in phantom and atherosclerotic plaque specimens to explorer the phase image methods with SWI sequence. Calcification (30% hydroxyapatite), hemorrhage (blood clot), and lipid phantoms (intralipid & cholesterol) were made in agar gel. Human enterectomy carotid specimens (n = 4) in saline solution were obtained for MRI scan. Multi-slice SWI sequence was a 3D FLASH sequence with flow compensation in read and slice directions (even no flow was presented). The imaging parameters included: TR/TE = 25 / 15.6 ms, flip angle = 20o, resolution = 0.1 x 0.1 x 1 mm, and 24-30 slices. Multi-contrast MRI scans were also performed in the specimen study as a comparison. The MRI system is a Siemens head-only 3T Allegra system with a single-channel volumetric coil of a 3-cm diameter. Raw data sets were reconstructed offline using a home-made software to provide both magnitude and phase images after phase unwrapping process. All phase data of plaque components were provided relative to the phase of adjacent agar gel (phantoms) or saline solution

(specimens). Pathological stains confirmed the existence of various plaque components. Results: Phantom Imaging: The quantitative phase data is shown in the Table, with consistent results between phantoms and carotid specimens. Calcification (diamagnetic) and hemorrhage (paramagnetic) show relatively large positive and negative phases, respectively (P < 0.01)

at TE of 15.6 ms. However, lipid has nearly zero phase change, which render difficult to indentify lipid in the phase image from other fibrotic tissue. Figure shows one example of carotid specimen images. The phase images can clearly identify the locations of calcification and hemorrhage that show hypointensity in other contrast images. 3D SWI imaging has advantages of less flow artifacts (3 directional flow compensations), thin slice thickness (1-2 mm), and possibly reduced scan times. Further effort is needed to explore contrast-enhanced 3D SWI for lipid identification. Conclusion: This ongoing study shows possibility of differentiating major plaque components using 3D SWI approach. In vivo study is currently under investigation with carotid plaque patients.

Phantoms Carotid Specimens

Calcification 1.02π ± 0.87 π 1.05π ± 0.46 π

Hemorrhage -0.6π ± 0.07 π -0.65π ± 0.08π

Lipid 0.1π ± 0.6 π -0.15π (lipid & IH)

Table Relative phase data of each plaque component

T1w

T2w

PDw

SWI

Lipid

Lipid

Phase

Lipid

Figure Various image contrasts of one carotid plaque specimen with the pathological image.Green = Hemorrhage, Blue = Calcification


12.7 Evaluation of Inflammatory Status of Atherosclerotic Carotid Plaque before Thromboendarterectomy using Delayed Contrast-enhanced Subtracted images after

Magnetic Resonance Angiography Giacomo DE Papini1,2, MD, Giovanni Di Leo1,2, DrSci, Stefania Tritella2, MD, Giovanni

Nano1,3, MD, Biagio Cotticelli2, MD, Claudio Clemente4, MD, Domenico G Tealdi1,3, MD, Francesco

Sardanelli1,2, MD 1Dipartimento di Scienze Medico-Chirurgiche, Università degli Studi di Milano, Milan, Italy 2Unit of Radiology, IRCCS Policlinico San Donato, San Donato Milanese, Italy 3Unit of Vascular Surgery, IRCCS Policlinico San Donato, San Donato Milanese, Italy 4Pathology Unit, Istituto Clinico Sant’Ambrogio, Milan, Italy Purpose: To prospectively investigate the correlation among carotid plaque contrast enhancement (CPCE) at contrast-enhanced magnetic resonance (MR) imaging, inflammatory cell infiltration (ICI) at histopathology, and the degree of carotid artery stenosis. Materials and Methods: Institutional Review Board approval and written informed consent were obtained. Twenty-eight patients (19 males, 9 females; mean age 67±9 years) scheduled for thromboendarterectomy prospectively underwent MR imaging at 1.5-T using: (a) an unenhanced axial 3D T1-weighted gradient-echo (T1wGRE) sequence centered on carotid bifurcations; (b) contrast-enhanced MR angiography (CE-MRA) with 0.1 mmol/kg of gadobenate dimeglumine; (c) the enhanced axial T1wGRE sequence as in point (a), acquired at 3 minutes after contrast injection. A three-point score system (absent, focal, or wide) was used to assess CPCE on native and subtracted (c minus a) MR images and ICI at histopathology. The degree of stenosis was determined using maximum intensity projections and multiplanar reformatted images from the CE-MRA study. Weighted Cohen k statistics, Chi-square test, and Spearman correlation coefficient were used. Results: Six CPCE studies were discarded due to patient movement. In the remaining 22 studies, CPCE was absent, focal and wide in 13, 6 and 3 cases, respectively, while ICI was absent, focal and wide in 13, 7 and 2 cases, respectively (moderate agreement; k=0.57). On CE-MRA 21/28 stenoses were severe and 7/28 moderate. There was no correlation either with ICI (P=1.000, n=28) or CPCE (P=.747, n=22). Conclusion: The correlation between CPCE and ICI suggests a role for CPCE as an independent marker of plaque inflammation.


12.8 A Targeted Contrast Agent Specific to Fibronectin for MR Molecular Imaging of Atherosclerotic Plaques

Xueming Wu, Wen Li, Xin Yu and Zheng–Rong Lu*

1Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio

Purpose: It has been reported that fibronectin accumulate in the extracellular matrix of atherosclerotic plaque tissues. It can be a viable molecular target for the detection of early plaque tissue with molecular imaging. The goal of this work is to develop a safe and effective targeted MRI contrast agent specific to the fibronectin in the extracellular matrix for molecular imaging of early atherosclerotic plaques. Methods: A low molecular weight targeted Gd-DOTA based contrast agent was synthesized by solid phase chemistry. Apolipoprotein E–deficient mice were used as the animal model of atherosclerotic plaques. The MRI study was performed under an approved protocol by the IACUC of Case Western Reserve University. The contrast agent was administered via a tail-vein injection catheter. Magnevist was used as a control agent. The MR images of abdominal aorta were acquired on a Bruker 9.4T animal MRI scanner using a T1-weighted sequence before and after contrast agent injection. Results: Figure 1 shows in vivo MR images acquired in an atherosclerosis animal model, ApoE-deficient mice, before and after injection of the targeted contrast agent and Magnevist. After injection of the targeted agent, strong enhancement of the aortic wall in ApoE-deficient mouse was observed. The enhancement lasted for the whole experiment period up to 95 minutes. Magnevist resulted in visible enhancement in the first 20 minutes after injection. The targeted contrast agent still showed 60.0 % increase of contrast-to-noise ratio [CNR] in the atherosclerotic plaques at 80 minutes after injection, while Magnevist resulted in only 4.2 % increase of CNR. The result indicates that the low molecular weight targeted MRI contrast agent can specifically bind to fibronectin in the extracellular matrix of atherosclerotic plaque tissue, resulting in strong and prolonged contrast enhancement. Conclusion: The novel targeted MRI contrast agent is effective for molecular imaging of stromal fibronectin in the atherosclerotic plaque tissue in the ApoE-deficient mouse model. The targeted contrast agent is promising for accurate detection of early atherosclerotic plaques with MRI.

Figure 1. T1-weighted axial MR images of abdominal aorta of ApoE-deficient mice before injection (pre) and up to 95 minutes after injection of targeted MRI contrast agent (top row) and Magnevist (bottom row). Arrows point to atherosclerotic aorta and insets are enlarged images of the aorta.

Pre 5 min 20 min 35 min 50 min 65 min 80 min 95 min


P.1 The Relationship of Asymmetric dilatation of Virchow-Robin space and Ipsilateral Internal Carotid Artery stenosis

on MRA Tae-Sub Chung, Ah Young Park, Sang Hyun Suh

Dept. of Radiology, Gangnam Severance Hospital, Yonsei University Medical college, Seoul, South Korea

Purpose: To test the hypothesis that chronic ischemia followed by white matter atrophy is associated with Virchow-Robin spaces (VRSs) dilatation by determining the relationship between ipsilateral internal carotid artery (ICA) stenosis and asymmetric dilatation of VRSs on the same side. Methods: We recruited patients with unilateral ICA stenosis and compared the degree of VRSs dilatation between ipsilateral and contralateral cerebral white matter. We retrospectively reviewed axial T2-weighted (TR/TE 3000/80, FoV 21x21) and diffusion weighted(TR/TE 4000/80, b=1000, FoV 24x24) MR images (GE Signa Excite 3T) of 46 patients with severe unilateral ICA stenosis (>70%), diagnosed by carotid contrast MRA between Feb. 2007 and Sep. 2009. Cases with contralateral ICA stenosis more than 50% were excluded. We optionally assessed the VRSs dilatation in the pre- and post-central gyri and corona radiata, along the corticospinal tract (CST) pathway on the basis of the fact that CST is a collection of large-caliber nerve fibers, vulnerable to ischemic degeneration and in easily identifiable locations. All lesions were graded into score 0 (None), score 1 (linear hyperintensity not extending to the corona radiata), score 2 (linear hyperintensity extending to the corona radiata) and score 3 (round or oval hyperintensity larger than 2mm). We statistically analyzed the difference of VRSs score between bilateral hemispheres, the correlation between VRSs score and severity of ICA stenosis, and the correlation between VRSs score and age. Results: The mean VRSs scores were 2.57 and 2.17 on the ipsilateral and contralateral sides, resulting statistical significance (p<0.01). The relationship between the patient’s age and VRSs score showed positive correlation (p<0.01 for ipsilateral and contralateral). However, there was no significant correlation between VRSs score and severity of ICA stenosis. Conclusion: Our results suggest that chronic ischemic process and subsequent white matter degeneration and atrophy is a factor of VRSs dilatation. Therefore, if we detect the unusual VRSs dilatation on brain MR, it is worth considering the possibility of ischemic condition and necessity of further workup such as MRA to evaluate the hidden stenosis in the ICA.


P.2 Protocol Optimization for Non-Contrast Enhanced MRA of the Abdominal Aorta at 1.5 and 3 T

Hua Guo1 1Department of Biomedical Engineering, Tsinghua University, Beijing, China

Purpose Non-contrast enhanced (NCE) MRA using inversion recovery TrueFisp has been successfully applied in the abdominal aorta imaging [1]. This technique is promising as an alternative or complementary tool to contrast-enhanced MRA [2]. However, in order to get comprehensive coverage from abdominal aorta to common iliac arteries with diagnostic values, imaging protocol needs careful adjustment. The purpose of this report was to find an optimal protocol for arterial spin labeling based NCE MRA at 1.5 and 3T. Methods The studies were performed at 1.5 and 3 T Siemens machines (Siemens, Erlangen, Germany) with two 8-channel phased array coils. 3D TrueFisp sequence with two inversion pulses were programmed so that the inversion slabs can be freely adjusted in either thickness or orientation. During imaging, the inversion slabs were prescribed in the transverse plane to suppress background signals and inflow veins. Imaging parameters were: image matrix=320x385, slice thickness=1.5 mm, FOV=363x400 mm2, IPAT along phase direction = 3, partial Fourier along slice direction = 6/8. Data acquisition was triggered by respiratory motion. For effective background signals and fat suppression, short-tau inversion-recovery (STIR) was employed prior to the TrueFisp sequence [1]. Optimal TI was selected to allow labeled arterial blood to fully fill in the abdominal aorta and common iliac arteries [3]. The cranial inversion slab was placed to cover the renal arteries and common iliac arteries properly. The second slab was positioned caudally to the first to suppress the vein inflows. It needs not to be contained within the FOV. For all the studies, healthy volunteers were recruited and provided informed written consent.

Results and Discussion Fig. 1 shows the abdominal aorta and common iliac arteries with good background signal suppression and extensive blood vessel coverage in the abdominopelvic cavity. In this study, we found that STIR provided better

heterogeneous background suppression than other fat suppression techniques (images not shown here). Additionally, respiratory triggering performed more reliably than navigator based technique. Conclusions We have demonstrated the optimal setup using inversion recovery TrueFisp for comprehensive coverage from suprarenal arteries to common iliac arteries. Further clinical studies are planned to evaluate its performance in patients with arterial disease. References [1] Shonai T, et al., J Magn Reson Imaging 2009, 29: 1471-1477. [2] Bley TA, et al., ISMRM 2010, 3768. [3] Atanasova IP, et al., ISMRM 2010, 3783.

Fig. 1. Abdominopelvic MRA. Images were acquired at 1.5T (a) and 3 T (b).

a b


P.3 The Effect of Omniscan on Hypoxia Inducible Factor-1α (HIF-1α) in Macrophages

Thomas A. Hope1, Alexis N. Brumwell2, Sarah E. Wheeler2, Robert C. Brasch1 and Harold Chapman2

1 Department of Radiology, University of California San Francisco 2 Department of Pulmonary and Critical Care, University of California San Francisco

Purpose: Nephrogenic Systemic Fibrosis (NSF) is a debilitating disease, which presents as a thickening of the skin often with contractures (Cowper 2000). It was relatively unknown to clinicians until 2006 when it was associated with the administration of gadolinium. We have done experiments in rats treated with high dose Omniscan showing that the coadminstration of intravenous iron and high dose erythropoietin significantly increases the severity of dermal lesions (Hope 2009). In light of the number of unbound electrons in the gadolinium ion and the role in which reactive oxygen species play in fibrosis, primarily through the regulation of hypoxia inducible factor-1α (HIF-1α, Lu 2005), we hypothesized that gadolinium disrupts the oxygen dependent regulation of HIF-1α resulting in increased fibrosis. Methods: RAW 264.7 mouse leukaemic monocyte macrophage cells were used in this experiment. Cells were cultured in Dulbecco’s modified Eagle’s medium for 24 hours prior to treatment, and then transferred to serum free media for the duration of the treatment periods. Omniscan (GE Healthcare, Oslo, Norway), gadodiamide, caldiomide, GdCl3, and FeSO4 were added to the serum free media at various concentrations as described. Cells were lysed in RIPA buffer. The Micro BCA technique was used for protein quantification, and 15 to 20 ug were run per well in each western blot. Anti-human/mouse/rat HIF-1α Antibody was purchased from R&D systems. Results: In the first experiment RAW cells were treated with various concentrations of Omniscan for three hours (Figure 1). HIF-1α protein levels rose in cells treated with 2.5 and 25 mM Omniscan, while 250 mM Omniscan was lethal to the cells. As a control, cells were cultured with various concentrations of caldiomide (the excess chelate administered along with gadodiamide in the clinical formulation of Omniscan) and GdCl3 (Figure 2). Caldiomide in a concentration of 1 and 10 mM resulted in an increase in HIF-1α levels as seen with the Omniscan, although the GdCl3 had no effect on HIF-1α levels. To further evaluate this effect we cultured cells with Omniscan and different concentrations of iron (Figure 3), which showed that the addition of iron to the cell culture prevented the accumulation of HIF-1α. Human cultured epithelial cells did not effect HIF-1α levels (data not shown). Additionally, treatment with gadodiamide did not increase HIF-1α levels. Conclusion: Our results demonstrate that gadodiamide does not result in an increase in HIF as hypothesized. Of note, the excess chelate administered along with gadodiamide in the formulation of Omniscan does lead to a rise in HIF-1α levels in an iron dependent mechanism. We stress that in the setting of cell culture, the excess chelate in the Omniscan formulation can have important physiologic effects on the cells, and therefore it is imperative to test results with both gadodiamide and caldiomide in order to determine if the excess chelate is in fact causing the observed physiologic changes. References: Cowper SE, Robin HS, Steinberg SM, Su LD, Gupta S, LeBoit PE. cleromyxoedema-like cutaneous diseases in renal-dialysis patients. Lancet. 2000 Sep 16;356(9234):1000-1. Hope TA, High WA, Leboit PE, Chaopathomkul B, Rogut VS, Herfkens RJ, Brasch RC. Nephrogenic systemic fibrosis in rats treated with erythropoietin and intravenous iron. Radiology. 2009 Nov;253(2):390-8. Lu H, Dalgard CL, Mohyeldin A, McFate T, Tait AS, Verma A. Reversible inactivation of HIF-1 prolyl hydroxylases allows cell metabolism to control basal HIF-1. J Biol Chem. 2005 Dec 23;280(51):41928-39. Epub 2005 Oct 13.


P.4 Use of contrast-enhancement and high-resolution 3D black-blood MR Imaging to identify inflammation in rabbit

atherosclerotic plaques Jin Hur, Jaeseok Park, Young Jin Kim, Hye-Jeong Lee, Kyu Ok Choe, and Byoung Wook

Choi Department of Radiology and Research Institute of Radiological Science, Yonsei

University College of Medicine, Seoul, South Korea

Background: Inflammation plays a critical role in plaque initiation, progression, and disruption. As such, inflammation represents an emerging target for the treatment of atherosclerosis. Purpose: We investigated the contributing factors for plaque enhancement and examined the relationships between regional contrast enhancement and the inflammatory activity of atherosclerotic plaques in an experimental rabbit model using contrast-enhanced high-resolution 3D black-blood magnetic resonance imaging (MRI) in comparison with histopathology. Methods: Ten atherosclerotic rabbits and three normal control rabbits underwent high-resolution 3D contrast-enhanced black-blood MRI. MR images and the corresponding histopathological sections were divided into four quadrants. Plaque composition was analyzed for each quadrant according to histopathological (percent of lipid-rich, fibrous, macrophage area and microvessel density) and imaging criteria (enhancement ratio (ER), ER=SIpost/SIpre). Results: A total of 62 non-calcified plaques (n=248, 156 lipid-rich quadrants and 92 fibrous quadrants) were identified based on histopathology. Mean ER values were significantly higher in atherosclerotic vessel walls than in normal vessel walls (2.03 ± 0.25 vs 1.58 ± 0.15, p = 0.017). Mean ER values were significantly higher in macrophage-rich plaques compared to the macrophage-poor plaques (2.21 ± 0.28 vs 1.81± 0.22, p = 0.008). Using multiple regression analysis, macrophage area and microvessel density were independently associated with ER values that reflected plaque enhancement (p <0.001). Conclusion: Contrast-enhanced high-resolution 3D black-blood MRI may be an efficient method to predict plaque inflammation. Key Words: Atherosclerosis; Magnetic resonance imaging; Plaque; Inflammation

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P.6 Magnetic Resonance Lymphangiography for the preoperative assessment of upper extremity lymphedema:

Preliminary data in patients undergoing autologous microsurgical lymph node transfer.

Tiffany Newman, MDI, Julie Vasile MD II, Joshua Levine, MD II, David Greenspun, MD II, MSc, Robert J. Allen M.D., A.P.M.C, F.A.C.S II, Kemi Babagbemi, MD I, Martin R. Prince,

MD, PhD I I Radiology, Weill Cornell Imaging at New York Presbyterian, New York, NY, United States,

II The Center for Microsurgical Breast Reconstruction, New York, NY, United States. Purpose: MR imaging of the lymphatic system to identify problematic sites of lymph flow has been well documented in the lower extremities with advantages over lymphoscintigraphy that include no radiation. A novel technique in its early stages of development involves autologous microsurgical lymph node transfer for the treatment of upper extremity lymphedema in patients post mastectomy and lymph node dissection. We preliminarily evaluate the development of our magnetic resonance lymphangiography technique with 3-D reconstruction for preoperative delineation of upper extremity lymphatic flow in lymphedema patients undergoing lymph node transfer surgery. Methods: We performed 3 MRL studies in patients with clinical lymphedema of one arm undergoing microsurgical lymph node transfer. Six upper extremities (control versus edema arm) were scanned at 1.5 Tesla (GE Signa HDx 14.0, Waukasha, Wisconsin). Three-dimensional LAVA was acquired in each patient of both upper extremities using 2.6mm slice thickness. The acquisition matrix was 512 x 200-512 with an acquisition time of 45 seconds to 2.5 minutes. A mixture of 15 ml of Gadodiamide (Omniscan) and 1 ml mepivicainhydrochloride (Carbocaine) 2% solution was mixed and subdivided into eight 2 ml portions for intradermal injection using a thin (27-gauge) needle. Each wrist was injected 3-4 times using sterile technique then massaged for 30 seconds. Parameters were TR/ TE/ flip = 4.1/1.9/15, bandwidth= 100 k Hz, NEX= 0.71. The images were post-processed on the Advantage Workstation using MIP reconstructions. Results: MR lymphangiography demonstrated obstruction of lymphatic flow in 2 of the 3 lymphedema extremities. The 3rd patient with presumed lymphatic abnormality without lymphedema secondary to increased right arm infections (from benign procedures) underwent MRL, which demonstrated fewer attenuated lymphatic channels with increased collateralization of flow in comparison to the control arm. Preliminary data reveals the utility of MR Lymphangiography in evaluating the lymphatic anatomy and pathology in patients with upper extremity lymphedema. MRL has the potential to estimate and localize areas of lymphatic obstruction when compared to the control arm. We estimated lymphatic transit time to the axilla to be 15-30 minutes in normal and abnormal arms, allowing determination of optimal scan timing. Conclusion: Limitations of small sample size and variations in technique exist, however future directions will explore surgical correlation with preoperative MRL studies and postoperative follow-up in more patients undergoing surgical lymph node transfer to evaluate MRL accuracy. References: Lohrmann C, Felmerer G, Speck O et al. Posteroperative Lymphoceles: Detection with High-resolution MR Lymphangiography. J VAsc Interv Radiol 2006; 17:1057-1062. Cheng-Hung L, Rozina A, Shin-Cheh S, et al. Vascularized Groin Lymph node Transfer Using the Wrist as Recipient Site for Management of Postmastectomy Upper Extremity Lymphedema. J Plast Reconstr Surg 2009; 123:1265-75.

Figures: Preoperative MRL of the upper extremties of the same patient.


P.7 Effect of stellate ganglion block on cerebrovascular system: MRA study

Seung-Taek Oh1, Chang-Ki Kang1, Dong-Yeon Kim2, Young-Bo Kim1, Zang-Hee Cho1 1. Neuroscience Research Institute, Gachon University of Medicine and Science, Korea

2. Dep. of Anesthesiology & Pain Medicine, Ewha Womans University, School of Medicine, Korea

PURPOSE: Several studies have shown that stellate ganglion block (SGB) is an effective treatment for certain cerebrovascular related diseases1-2; however, the direct effect of SGB on the cerebral vasculature is still unknown 3-4. The present study is to investigate the effect of SGB on the cerebral vascular system using magnetic resonance angiography. METHODS: Time-of-flight magnetic resonance angiography images of nineteen healthy female volunteers (mean ages of 46.4±8.9) were obtained before and after SGB with 1.5T magnetic resonance imaging. SGB was performed by injecting 6 ml of 1% mepivacaine at the anterior tubercle of the sixth cervical transverse process. Successful interruption of sympathetic innervation to the head was determined by the appearance of Horner's syndrome and conjunctival injection. We measured changes in the average signal intensity and diameter of the major intracranial and extracranial arteries and their branches. RESULTS: The signal intensity changes were observed mainly in the ipsilateral extracranial vessels and compared with before and after SGB; the external carotid artery (11.2%) and its downstream branches, such as the occipital artery (9.5%) and superficial temporal artery (14.1%). In contrast, the intensities of the intracranial arteries did not change with the exception of the ipsilateral ophthalmic artery, which increased significantly (10.0%). Following SGB, only the diameter of the ipsilateral external carotid artery was significantly increased (26.5%). CONCLUSION: We were able to observe significant changes in the extracranial vessels, while the intracranial vessels were relatively unaffected except for the ophthalmic artery, demonstrating that each of perivascular nerve control and sympathetic nerve control mechanisms may contribute to the control of intracranial and extracranial blood vessels following SGB, respectively. REFERENCES: 1. Lipov EG, et. al., Lancet Oncol 2008; 523 2. Mazin E. Pain Physician 2000; 294 3. Wagerle LC, et. al., Am J Physiol 1983; H487 4. Busija DW, et. al., Circ Res 1980; 696


P.8 Dynamic 3D MR Angiography for the Assessment of Rheumatoid Disease of the Hand

Sabine Weckbach1, Mike Notohamiprodjo1, Christian Glaser1, Hans Hatz2, Maximilian Reiser1

1Department of Clinical Radiology, University Hospitals Munich, Campus Grosshadern, Germany, 2Department of Rheumatology, Benedictus Hospital for Rheumatoid diseases,

Feldafing, Germany Purpose: To investigate highly temporally resolved MR Angiography (MRA) of the hand as supplementary tool for dynamic assessment of synovitis and vascular pathologies in rheumatoid diseases. Methods: A coronal dynamic 3D MRA sequence (TWIST: 0.7x0.7x3.0 mm3, temporal resolution 2.2 sec, time of acquisition 3 min) of the predominantly affected hand of 17 patients with suspected rheumatoid disease was acquired during contrast administration (Multihance, Bracco Imaging SpA, Italy) on a 3.0 T MR system (MAGNETOM Verio / 8-channel-knee-coil, Siemens Healthcare, Germany). As standard of reference high resolution non fat-saturated coronal and fat-saturated axial post contrast T1-w SE sequences were acquired afterwards. These static sequences and the dynamic 3D MRA maximum intensity projections (MIP) were separately assessed by two readers in consensus, recording the number of synovial lesions (wrist, intercarpal, metacarpophaleangal/proximal/distal interphalangeal joints), signs of tenosynovitis and vasculitis. Diagnostic confidence was rated (4-point-scale: 4=excellent; 1=non-diagnostic). Statistical significance was tested (paired t-tests). Results: The 3D MRA MIP provides a fast diagnostic overview of inflammatory lesions in the hand of patients with rheumatoid arthritis (RA) (Fig. 1 A, B). However, compared to true morphological sequences (Fig. 1 C, D) a significantly lower number of joints with synovitis (n=66 vs. 89; p<0.05) and only 3/9 cases with tenosynovitis were identified by the 3D MRA MIP. For detected inflammatory lesions, diagnostic confidence was comparable (MRA: 3.64; static T1-w post contrast: 3.47). In 5 patients with high clinical disease activity dynamic MRA showed very early synovial enhancement (Fig. 1 E, F) not present in patients with clinically moderate and low disease activity. Only dynamic MRA detected 3 cases of vasculitis which subsequently were clinically confirmed by digital subtraction angiography (DSA) (Fig. 1 G, H). Conclusions: The 3D MRA MIP facilitates fast detection of synovitis. Although dynamic MRA of the hand is inferior to true morphological static contrast enhanced sequences in assessing the number of synovitic and tenosynovitic lesions, its high temporal resolution allows for grading of disease activity and assessment of vasculitis without additional contrast material application. In additional ongoing studies highly temporally resolved MRA is used for MR-quantification of perfusion and endothelial permeability especially with respect to therapy control in rheumatoid diseases.

Fig. 1: 3D MRA MIP providing a faster diagnostic overview of (A, @ 18 sec post contrast) synovitis and (B, @ 50 sec) additional tenosynovitis than standard morphological contrast enhanced sequences (C non fat-saturated T1-w, D fat saturated T1-w) in a 42 y/o female with active RA. Early phase (E, @ 10 sec) of a 3D MRA MIP depicting very early synovial enhancement indicating high clinical disease activity in a 30 y/o female with RA with confirmation of severe synovitis in later phases (F, @60 sec). 3D MRA MIP (G, @ 10 sec) showing irregularities, rarification and occlusion of small arteries as signs of vasculitis in a 22 y/o female with (H) DSA correlation.


P.9 Time-Resolved MR Angiography for Detecting and Grading Ovarian Venous Reflux: Comparison with

Conventional Venography Dal Mo Yang, Hyun Cheol Kim, Geon-Ho Jahng

Dept of Radiology, East-West Neo Medical Center , Kyung Hee University Purpose: The purpose of this study was to compare the diagnostic accuracy of time-resolved MR angiography (TR-MRA) with that of conventional venography for the detection and grading of ovarian venous reflux, which aid for a diagnosis of pelvic venous congestion. Methods: We performed a retrospective analysis of 19 consecutive patients who underwent TR-MRA and conventional venography. The images were analyzed by two radiologists in a randomized ‘blinded’ manner. With the use of conventional venography as a gold standard, the images were reviewed to determine if differences in the detection and grading of ovarian venous reflux were seen between TR-MRA and conventional venography, and the sensitivity, specificity and accuracy of TR-MRA, as compared with that of conventional venography, were evaluated. The McNemar test was performed to determine the significance of any differences. Interobserver agreement was analyzed using generalized κ statistics. Results: There was no significant difference between TR-MRA and conventional venography for grading ovarian venous reflux (P > 0.05). The sensitivity, specificity and diagnostic accuracy of TR-MRA were found to be 66.7%, 100% and 78.9%, and 75%, 100% and 84.2%, respectively, for the two observers. The weighted κ values indicated excellent agreement between the two observers for grading ovarian venous reflux on TR-MRA (κ = 0.894). Conclusions: TR-MRA is an accurate method for accessing pelvic venous congestion. References 1. Hiromura T, Nishioka T, Nishioka S, et al. AJR 2004 ;183 :1411-1415 2. Kim HS, Malhotra AD, Rowe PC, et al. J Vas Interv Radiol 2006 ;17 :289-297 3. Asciutto G, Mumme A, Marpe B, et al. Eur J Vasc Endovasc Surg 2008 ;36 :491-496


P.10 Diagnosis of Vertebral Artery Ostial Stenosis on Contrast-Enhanced MR Angiography: Usefulness of a Thin-

Slab MIP Technique Sun Mi Kim1, Jin Woo Choi3, Byung Se Choi4, Hyun Sin In5, Deok Hee Lee2

1Department of Radiology, East-West Neo Medical Center, Kyung Hee University, 2Department of Radiology and Research Institute of Radiology, University of Ulsan

College of Medicine, Asan Medical Center, Seoul, South Korea, 3Department of Radiology, Konkuk University Hospital, Konkuk University School of Medicine, Hwayang-dong,

Gwangjin-gu, Seoul, Korea, 4Department of Radiology, Seoul National University Bundang Hospital, Republic of Korea, 5Department of Radiology, Busan Paik Hospital, Inje

University College of Medicine, Busan, Republic of Korea Purpose : To differentiate pseudostenosis of veretebral artery ostium from true stenosis using thin-slab maximum-intensity-projection(MIP) images of the ctrast-enhanced magnetic resonance angiography (CE-MRA) Methods: MR imaging was performed on a 3.0-T MR system equipped with a neurovascular head and neck coil. High-spatial-resolution 3D CEMRA was obtained in the coronal plane using a fast–field, gradient-echo sequence together with the contrast-enhanced timing robust angiography k-space acquisition technique which is a modified centric k-space ordering technique. We used a PC-based, 3D image processing software (Aquarius NET; TeraRecon, San Mateo, CA). When there was any stenosis at the VA os, we re-evaluated the degree of stenosis using thin-slab MIP images (slab thickness of 1mm) with variable direction and which followed the course-of VA from the os to the proximal VA. Results: VA os stenosis was overestimated on MIP images of CE MRA. Therefore, we tend to underestimate the degree of VA os stenosis in our daily clinical practice. Considering these problems, a simple, PC-based review of a lesion using a thin-slab MIP technique is very helpful in order to both minimize possible exaggeration of the stenosis on images as well as the potential clinical underestimation of a possible, existing stenosis. Conclusion: A PC-based, thin-slab MIP reconstruction technique is useful for differentiating true stenosis from pseudostenosis of the VA ostia.


P.11 Separating Coherent Aliasing from Incoherent Artifacts in a Highly Undersampled Acquisition - A Point Object Experiment

1aR. Busse, 2aK. Wang, 1aJ. Holmes, 1bP. Beatty, 1aJ. Brittain, 2a,bF. Korosec 1Applied Science Lab, GE Healthcare, aMadison, WI, bMenlo Park, CA

2aMedical Physics, 2bRadiology, University of Wisconsin-Madison, Madison, WI Purpose: To investigate a rapid parallel imaging approach to resolve coherent aliasing from a highly-undersampled acquisition. Methods: A small syringe phantom (<4 mm in diameter) was scanned with a large FOV to simulate a small vessel in cross-section (appearing in the ky-kz plane as a point object). A set of fully-sampled 3D Cartesian data were acquired with an 8-channel head coil, with matrix size of 32 (readout) x 240 x 120 and a FOV of 48 x 48 x 24 cm3. The data were reconstructed as follows, shown in Fig. 1: Column (a): FFT on fully-sampled data; (b): FFT on data uniformly-subsampled (2×2); (c): FFT on data further subsampled by 4× using Interleaved Variable Density (IVD) [1]; (d): ARC [2] reconstruction of same data, where ARC is calibrated for uniformly-undersampled data but applied to the 16-fold undersampled dataset in the ARC synthesis phase. (e): ARC reconstruction of the same data but is calibrated for the true sampling pattern in (c). (f): FFT on data under-sampled by ×4 using IVD only. Results & Discussion: Fig. 1 second row shows the reconstructed images, which can be interpreted as the point spread function (PSF). The last row shows the line profiles across the center of the PSF images (dashed line). Coherent artifacts expected when reconstructing by zero-fill (columns b and c) are removed by ARC (columns d and e), even when ARC is calibrated for an “incorrect” regularly-spaced sampling pattern. This technique leaves only incoherent artifacts, similar to a zero-fill reconstruction of IVD-undersampled data (column f). Calibrating on the “correct” undersampling pattern partially removes the incoherent artifacts as well as the coherent artifacts. However, because the very low sampling density requires a very large kernel and a large number of patterns, reconstruction time was 160x greater. Conclusion: Because incoherent artifacts are often benign, a rapid reconstruction using an “incorrectly” calibrated reconstruction may prove useful for time-resolved angiography in a clinical setting that requires immediate visualization of results. This technique also enables PI to be used as a first step of a rapid constrained reconstruction, such as Cartesian HYPR [3]. References: [1] Busse, ISMRM 2009, p4534. [2] Brau, MRM 59:382 (2008) [3] Wang, ISMRM 2010, p352

Figure 1. Results from the PSF analysis. Column (a): fully-sampled; (b): uniformly undersampled (2×2); (c): uniformly and IVD undersampled (×16); (d): ARC applied to regularly and IVD undersampled data, where ARC is calibrated for a ×4 regularly-undersampled data, but applied to the ×16 undersampled data in the synthesis phase. (e): ARC applied to data in (c) but is calibrated for the true smapling pattern. (f): IVD undersampled ×4 alone.


P.12 Towards Real-Time MR-Guided Transarterial Aortic Valve Implantation (TAVI): In vivo Evaluation in Swine

Harald H. Quick1,2, Philipp Kahlert3, Holger Eggebrecht3, Gernot M. Kaiser4, Nina Parohl2, Juliane Albert2, Ian McDougall5, Raimund Erbel3, Mark E. Ladd2

1Institute of Medical Physics, Friedrich-Alexander University Erlangen-Nürnberg, Germany 2Institute of Diagnostic and Interventional Radiology, University Hospital Essen, Germany

3Department of Cardiology, Heart Center Essen, University Hospital Essen, Germany 4Department of Transplantation Surgery University Hospital Essen, Germany

5Evasc Medical Systems, Vancouver, BC, Canada Purpose: MR-guided transcatheter, transarterial aortic valve implantation (TAVI) has been performed in swine following device modifications towards magnetic resonance (MR) compatibility of a comercially available stent valve delivery device. Methods: The self-expandable Medtronic CoreValve® aortic bioprosthesis (Medtronic, Inc., Minneapolis, MN, USA) is composed of a nitinol stent frame with an integrated trileaflet porcine pericardial tissue valve and is either implanted via the femoral or subclavian artery. Its delivery catheter has a 12 Fr shaft with 18 Fr distal end comprising the crimped prosthesis which can be released stepwise with continuous transaortic blood flow. The original catheter shaft revealed ferromagnetic braiding, considerably compromizing MR imaging and MR safety. Device modifications obviating any metal braiding resulted in full MR compatibility of the delivery device. MR-guided TAVI was performed on 8 farm pigs (75-85 kg) via subclavian access on a 1.5 T MRI system (Avanto, Siemens Healthcare, Germany) equipped with an interventional in-room monitor. Catheter placement and stent release was performed under real-time MR guidance with a rt-TrueFISP sequence providing 5 fps. Results: Device modifications resulted in artifact elimination and excellent real-time visualization of catheter movement and valve deployment using rt-TrueFISP imaging. MR-guided TAVI was successful in 6/8 swine. Post-interventional therapeutic success could be confirmed using ECG-triggered cine-TrueFISP sequences and flow-sensitive phase contrast sequences revealing or excluding regurgitation, respectively. Final stent valve position was confirmed by ex vivo histology. Conclusions: The self-expandable CoreValve aortic stent-valve is potentially suited for real-time MRI-guided placement after suggested design modifications of the delivery-system. MR imaging in this interventional setup provided excellent pre-interventional anatomic and functional evaluation of the native aortic valve, precise real-time instrument guidance allowing accurate placement of the stent-valve within the native aortic annulus, and finally detailed post-interventional evaluation of therapeutic success.


P.13 Follow-up of y Knife treated arteriovenous malformations: usefulness of 4D MR Angiography and 3D GE

Steady State acquisition after gadobutrol at 3T N. Anzalone, E. Ventura, P. Picozzi°, F.Scomazzoni, A. Iadanza

Dept of Neuroradiology and Neurosurgery°, Scientific Hospital HS Raffaele, Milan, Italy

Purpose: data from a previous study on follow-up of radiosurgery treated arteriovenous malformations (AVMs) have demonstrated high diagnostic accuracy of MRA at 3T after blood pool contrast media (Vasovist, Bayerscheringpharma,Berlin) in comparison with DSA. The purpose of the present study was to prospectively evaluate the feasibility and the diagnostic value of contrast-enhanced magnetic resonance angiography with dynamic acquisition and with high resolution 3 D FEE acquisition at 3T after gadobutrol (Gadovist, Bayerscheringpharma,Berlin) in the follow up of cerebral AVMs treated with y knife radiosurgery. Materials and methods: since January 2009, 22 patients treated with y knife radiosurgery for the presence of a cerebral AVM were prospectively evaluated. Mean time between treatment and control MRA was 15 months (range 3-48 months). All patients have been studied at 3T ( Intera, Philips Medical System, Best) with 4D Track MRA ;fifty dynamic scans were obtained with a temporal resolution of 608 msec and a spatial resolution of (1.1x1.4x1.1)mm3 after power –injection of 0.1ml/Kg of gadobutrol. Then a high spatial resolution 3D FEE “steady state” sequence (TR25msec, TE3,7msec;slice thickness0.5mm,matrix512x512,field of view240) was obtained. Row images from 3D FEE were sent on a separate workstation (Viewforum Release 5.1,Philips Medical System) and reconstructed in multiplanar MIP projections.4D MRA studies and 3D FEE reconstructed studies were then compared with pre -treatment DSA exams, as usually performed in the normal clinical setting, to look for reduction of nidus size , of arterial feeders and venous drainage. DSA was then performed in 3 patients were complete occlusion of AVM was suspected at MRA. Results: evaluation of 3DFEE reconstructed images revealed in 13 cases reduction of the nidus size and /or of venous drainage, in 5 cases persistence with no modification of the AVM and in 4 cases complete occlusion of the malformation, confermed at DSA in 3 cases. All persistent AVMs were > 3cm in nidus size, whereas both occluded and reduced malformations were lower than <3cm in size. Evaluation of 4D MRA confirmed the data reported from 3D FEE studies in the assesment of occlusion or persistence of the malformation, but didn’t identify all arterial feeders shown at 3D FEE acquisition. Conclusion: MRA with gadobutrol at 3T in the follow-up of cerebral AVMs treated with yknife resulted to be feasible and accurate .Nevertheless 3D FEE high resoluted acquisition showed to be more accurate than 4D technique in the complete evaluation of the residual malformation.


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Tim+Dot offer high resolution whole body angio with no patient repositioning. Angio Dot Engine guides for high-quality images - MAGNETOM Aera 1.5T and Skyra 3T. Siemens. Answers for life. www.siemens.com/mr

TopSpins Inc. is dedicated to helping MR imaging centers implement safe, accurate, state-of-the-art contrast enhanced MR Angiography and dynamic contrast-enhanced MR imaging studies for the benefit of their patients. www.topspins.com Robarts Research Institute harnesses the power of cell biology, genomics and advanced imaging technologies to investigate disorders of the neurological, cardiovascular and immune systems. It is a research Institute within the Schulich School of Medicine & Dentistry at The University of Western Ontario. www.robarts.ca

Founded in 1878, The University of Western Ontario is one of Canada's oldest universities and today is committed to providing the best student experience among Canada's leading research-intensive universities. A vibrant centre of learning located in London, Ontario, Western is home to more than 30,000 students and attracts external support of over $200 million annually for research projects. www.uwo.ca Seoul St. Mary's Hospital has 26 clinical divisions and 169 special clinics that are dedicated to providing professional medical services and conducting medical research. Seoul St. Mary's Hospital is making continued efforts to play a leading role in the international medical world as a university hospital affiliated to the Catholic University of Korea School of Medicine and Catholic Research Institute of Medical Science with a comprehensive health care system composed of nine health care and special clinical centers. www.cmcseoul.or.kr


Central Medical Service Ltd.(CMS) was established in 2007. Our company is contrast media specialty company for CT and MRI. We have produced our goods based on the knowledge and experience in the field of the chemical engineering. CMS is providing Bonorex , a locally-manufactured contrast medium for X-ray and CT, Bono-I, cotrast medium for MRI including 5ml vial for neonate and pediatrics. We have continuously trying to develop the effective products for CT and MRI. www.cmscorea.co.kr

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Presenter Index PageA Ahn, Chang-Beom 9.3 Removal of Eddy-Current Effects in Multiphase Cardiac Flow Imaging Co-authors: Pan-Ki Kim, Sang-Heum Cho, Jin-Ho Park

83

Anzalone, Nicoletta P13. Follow-up of y Knife treated arteriovenous malformations: usefulness of 4D MR Angiography and 3D GE Steady State acquisition after gadobutrol at 3T Co-authors: E. Ventura, P. Picozzi°, F.Scomazzoni, A. Iadanza

124

Aschauer, Manuela 2.7 Imaging of thromboembolic disease with MRA/MRV Co-authors: ElstnerJ.,Obernosterer A., Univ. Hospital. GRAZ, Austria

35

Atanasova, Iliyana 5.3 3 Station Non-contrast-enhanced Angiography of the Aortoiliac and Lower Extremity Arteries at 1.5T Co-authors: R.P. Lim, D. Kim, P. Storey, V.S. Lee

55

B Barker, Alex J 7.3 Acceleration-sensitive MRI: Analysis of Complex Vascular Flow Patterns Acceleration-sensitive MRI: Analysis of Complex Vascular Flow Patterns Co-authors: Felix Staehle, Simon Bauer, Bernd Jung, Michael Markl

67

Bernstein, MA 8.1 Compressive Sensing Reconstruction Improves Low-contrast Detectabililty Co-authors: JD Trzasko, A Manduca, Z Bao, KP McGee, Y Shu, J Huston III

74

Bley, Thorsten 3.8 High resolution vessel wall imaging in giant cell arteritis: 7 years experience Co-authors: J. Geiger, M. Markl, O. Wieben, M Uhl

45

Bock, Jelena 3.4 4D Pressure Difference Mapping in the Aorta Co-authors: R. Lorenz, A. Harloff, M. Markl

41

Brodsky, Ethan 6.3 Fat-Suppressed Steady State Imaging for Non-Contrast Enhanced MR Angiography in the Thorax & Abdomen Co-authors: Jessica Klaers, Kevin Johnson, Eric Bultman, Chris François, Scott Reeder, Walter Block 7.6 Developing Guidelines for Successfully Interleaving Active Tracking of Catheters with Steady-state Imaging Sequences Co-authors: B. Grabow, O Unal, W.F. Block

64

70

Brown, Jeff 2.1 Signal quality of single dose gadobenate dimeglumine pulmonary MRA examinations exceeds quality of MRA performed with double dose standard gadolinium-based agent Co-authors: Pamela K. Woodard, Thomas L. Chenevert, H. Dirk Sostman, Kathleen A. Jablonski, Paul D. Stein, Lawrence R. Goodman, Frank J. Londy, Vamsidhar Narra, Charles A. Hales, Russell D. Hull, Victor F. Tapson, John G. Weg.

29

Busse, Reed P11. Separating Coherent Aliasing from Incoherent Artifacts in a Highly Undersampled Acquisition - A Point Object Experiment. Co-authors: K. Wang, J. Holmes, P. Beatty, J. Brittain, F. Korosec

122


C Cadioli, Marcello 3.2 7D PC MRI to study Helical Blood Flow in the Human Aorta Co-authors: Morbiducci U., Ponzini R., Rizzo G., Cadioli M., Esposito A., De Cobelli F., Del Maschio A., Montevecchi F., Redaelli A.

39

Choi, Grace 9.7 ECG-Gating for MRA Co-authors: Zhitong Zou, Kana Fujikura, Martin R. Prince

87

Chung, Tae-Sub P1. The Relationship of Asymmetric dilatation of Virchow-Robin space and Ipsilateral Internal Carotid Artery stenosis on MRA Co-authors: Ah Young Park, Sang Hyun Suh

112

Cooper, Mitch 5.4 Three Dimensional Non-Contrast MRA of the Lower Extremities with Stepping Thin Slab Acquisition: A Feasibility Study in Healthy Subjects Co-authors: Thanh D. Nguyen, Pascal Spincemaille, Martin R. Prince, Yi Wang

56

D Diedrich, Karl 4.3 Stability of vascular centerlines and peak tortuosity measurements Co-authors: John Roberts, Richard Schmidt, Dennis Parker

48

E Ebner, Franz 4.1 How accurate are CE and TOF MRA at high field strengh (3.0.T) in assessing morphology and size of reperfusion of cerebral aneurysms after endovascular coiling Co-authors: U.Wiesspeiner, R.Vollmann, M.Augustin

46

F Fan, Zhaoyang 2.8 Noncontrast MRA of the hand using mutli-directional flow-sensitive dephasing preparation Co-authors: Hodnett P, Davarpanah A, Scanlon T, Sheehan J, Carr J, Li D

36

Foll, Daniela 9.4 Left ventricular MR velocity mapping: radial and long-axis dyssynchrony Co-authors: B. Jung, E. Schilli, F. Staehle, Ch. Bode, J. Hennig, M. Markl

84

Frayne, Richard 2.9 The Canadian Atherosclerosis Imaging Network – A Frame Work for Pan-Canadian, Multi-modality Vascular Imaging Studies

37

Fujikura, Kana 2.2 Features of COPD on time-resolved Pulmonary MRA Co-authors: Wei Zhang, Corey Ventetuolo, Joao Lima, David Bluemke, Graham Barr, Martin R. Prince

30

G Geerts, Liesbeth 7.7 An automated approach to vessel lumen analysis – Vessel Explorer Co-authors: Javier Olivan Bescos, Jeroen Sonnemans, Raymond Habets, Joost Peters

71

Guo, Hua P2. Protocol Optimization for Non-Contrast Enhanced MRA of the Abdominal Aorta at 1.5 and 3 T

113


H Hadizadeh, Dariusch 11.4 High-spatial resolution time-resolved 4D MR angiography of cerebral arteriovenous malformations: experience in 50 patients using different MRA protocols and different contrast agents Co-authors: Kukuk GM, Gieseke J, Tschampa H, Kovács A, Greschus S, Urbach H, Bostroem A, Schild HH, Willinek WA

101

Hahn, G. 1.4 Safety of 1.0M macrocyclic gadobutrol in mr angiography in pediatric patients – A German multicenter analysis Co-authors: W. Hirsch, H.J. Mentzel

27

Hope, Thomas A. P3. The Effect of Omniscan on Hypoxia Inducible Factor-1α (HIF-1α) in Macrophages Co-authors: Alexis N. Brumwell, Sarah E. Wheeler, Robert C. Brasch, Harold Chapman

114

Huff, Sandra 5.1 Continuously Moving Table Venography and Arteriography Co-authors: Michael Markl, Ute Ludwig

53

Hur, Jin P4. Use of contrast-enhancement and high-resolution 3D black-blood MR Imaging to identify inflammation in rabbit atherosclerotic plaques Co-authors: Jaeseok Park, Young Jin Kim, Hye-Jeong Lee, Kyu Ok Choe, Byoung Wook Choi

115

Huston, John 4.2 New Natural History Findings Utilizing MRA for the Study of Intracranial Aneurysms Co-authors: Robert Brown, Matt Bernstein, Steve Riederer

47

I Igase, Keiji 11.6 Effectiveness of Fat-Suppression MRAngiography Comparing with Standard 3D-TOF MRA in Revealing Cerebrovascular Diseases. Co-authors: Ichiro Matsubara, Masamori Arai, Jyunji Goishi, Kazuhiko Sadamoto

103

Isoda, Haruo 4.6 Magnetic resonance fluid dynamics of growing intracranial aneurysms Co-authors: Hisaya Hiramatsu, Shuhei Yamashita, Yasuo Takehara, Takehiro Naitoh, Takashi Kosugi, Toshiyasu Shimizu, Hiroyasu Takeda, Masaki Terada, Tetsuya Wakayama, Marcus T. Alley, Shigeru Miyachi, Harumi Sakahara

51


J Johnson, Kevin 3.6 Hemodynamic features of the cerebral dural sinuses demonstrated by PC VIPR MRV Co-authors: Ben Landgraf, Warren Chang, Michael Loecher, Yijing Wu, Steven Kecskemeti, Aaron Field, Oliver Wieben, Charles Mistretta, Patrick Turski

43

Johnson, Casey P. 8.6 Time-Resolved Calf-Foot 3D Bolus-Chase MRA Co-authors: Eric A. Borisch, Petrice M. Mostardi, James F. Glockner, Phillip M. Young, Stephen J. Riederer

79

Johnson, Kevin M. 10.9 Rapid Angiography and Perfusion with Multi-Echo 3D Radials and an Echo Weighted Constrained Reconstruction Co-authors: Ethan Brodsky, Alexey Samsonov, Walter Block, Oliver Wieben, Scott B Reeder

97

K Kanal, Emanuel 1.1 Decrease in acute adverse reactions to gadobenate dimeglumine 24

Kang, Chang-Ki 7.8 Potentials of ultra high field strength 7T MRA: Comparison with other imaging modalities Co-authors: Young-Bo Kim, Zang-Hee Cho

72

Kecskemeti, Steven 4.7 Accelerated 4D Phase Contrast Velocimetry of Intracranial Aneurysms Co-authors: Kevin Johnson, Yijing Wu, Patrick Turski, Oliver Wieben

52

Keith, Lauren 8.4 Parallel Imaging with Hybrid 3D Radial Acquisition for HYPR Reconstruction Co-authors: K. Wang, J. Holmes, F. Korosec

77

Kim, Dong-hyun 4.4 Accurate aneurysm morphometry using variable view angle tilting acquisition and super-resolution reconstruction Co-authors: MinOh Ghim, Sang-Young Zho, DongJoon Kim

49

Kim, Bum-soo 12.1 Supra-aortic Vascular Pathologies on Low Dose Time-Resolved CEMRA Co-authors: Jee Hyun Seok, So-Lyung Jung, Kook-Jin Ahn

105

Kim, Seong-Eun P5. Arterial Spin Labeling Perfusion Measurement using 3D single shot Stimulated Echo Planer Imaging (3D ss-STEPI) and FAIR at 3 Tesla Co-authors: Ji Kang Park, Eun-Kee Jeong, Dennis L Parker

116

Kim, SunMi P10. Diagnosis of Vertebral Artery Ostial Stenosis on Contrast-Enhanced MR Angiography: Usefulness of a Thin-Slab MIP Technique Co-authors: Jin Woo Choi, Byung Se Choi, Hyun Sin In, Deok Hee Lee

121

Koktzoglou, Ioannis 5.2 FERAL MR Angiography for Rapid, Quantitative Flow Imaging of the Peripheral Arteries Co-authors: Robert R. Edelman, Erik Offerman, Christopher Glielmi

54

Koktzoglou, Ioannis 5.8 Highly Accelerated Contrast-Enhanced MRA: Benefit of Complex SubtractionCo-authors: John J. Sheehan, Eugene E. Dunkle, Wei Li, Felix A. Breuer, Robert R. Edelman

60


Kukuk, Guido M. 2.6 Prevalence of deep venous thrombosis as detected by magnetic resonance thrombus imaging with a blood pool contrast agent in patients with suspected peripheral arterial disease Co-authors: Dariusch Hadizadeh, Ute Fahlenkamp, Arne Koscielny, Frauke Verrel, Hans H. Schild, Winfried A. Willinek

34

L Lanzman, RotemS 11.3 Nonenhanced ECG-gated time-resolved 4D Steady-State Free Precession MR Angiography (4D SSFP MRA) in assessment of intracranial collateral flow: comparison with digital subtraction angiography (DSA). Co-authors: Kröpil P, Schmitt P, Bi X, Miese FR, Hänngi D, Turowski B, Scherer A, Blondin D

100

Lee, Nahee 7.4 Multivariate Measurement of Trans-stenotic Pressure Gradient Co-authors: Sejin Heo, Suyoung Yoon, Junghun Kim, Younghae Do, Chelwoo Park, Jongmin Lee

68

Lee, Hwayoung Kate 7.9 Web Based MRA Protocols Co-authors: Satre Stuelke, Michelle Cerilles, Martin R Prince

73

Leiner, Tim 2.5 Evaluation of the long-term consequences of deep venous thrombosis using bloodpool enhanced MRI Co-authors: Carsten Arnoldussen, Joachim E. Wildberger, Cees Wittens, Michiel W. de Haan

33

Li, Rui 12.5 Quantitative Measurement of MR Constants in Carotid Plaque at 3T Co-authors: Jie Sun, Marina S. Ferguson, and Chun Yuan

108

Liu, Jing 9.1 Self-Gated Free Breathing 3D Coronary Cine Imaging With Simultaneous Water and Fat Visualization Co-authors: Thanh D. Nguyen, Jonathan Weinsaft, Martin R. Prince, Yi Wang

81

Lorenz, Ramona 3.7 Correction methods for streamline visualization in the aorta and the superior sagittal sinus of healthy volunteers Co-authors: J. Bock, J. G. Korvink, M.Markl

44

Lu, ZR 12.8 A Targeted Contrast Agent Specific to Fibronectin for MR Molecular Imaging of Atherosclerotic Plaques Co-authors: Xueming Wu, Wen Li, Xin Yu

111

M Maki, Jeffrey H. 5.7 A Timing Algorithm Strategy for pMRA Co-authors: George R. Oliveira, Gregory J. Wilson

59

Markl, Michael 3.3 4D Flow and Plaque Imaging in the Descending Aorta: Stroke Risk by Retrograde Embolization Co-authors: J. Simon, S. Brendecke, J. Bock, R. Lorenz, A. Harloff

40


Masui, Takayuki 10.5 Evaluation of the renal arteries using two types of Non-contrast MRA: FIESTA with flow preparation pulse and FIESTA with Inhance Inflow IR technique Co-authors: Motoyuki Katayama, Kimihiko Sato, Hiroki Ikuma, Takuma Terauchi, Masayoshi Sugimura, Naoyuki Takei, Mitsuharu Miyoshi, Tetsuji Tsukamoto, Hiroyuki Kabasawa

93

Meaney, Jim 5.5 Effective 5-station whole body contrast-enhanced MRA at 3T with reduced contrast dose, tourniquet thigh compression, and combined neurovascular coil and body coil. Co-authors: S. Barry, G. Cunnane, N. O Mahony, M. Knox, R. Dunne, G. Boyle, A. Fagan

57

Mendes, Jason 12.2 CINE Turbo Spin Echo Imaging Co-authors: Dennis L. Parker, Ph.D. and Jordan Hulet

106

Miki, Hitoshi 11.7 3-Tesla VR Images of Brain Tumor: Pre-surgical planning Co-authors: S. Oda, K. Kikuchi, S. Ohue, T. Mochizuki

104

Miyazaki, Mitsue 10.3 Non-Contrast MRA at 3T Co-authors: Yuichi Yamashita, Andrew Wheaton, Wayne Dannels, Masaaki Umeda, Masao Yui, Hitoshi Kanazawa, Satoshi Sugiura

91

Miyoshi, Mitsuharu 7.2 Phantom study of Black Blood CUBE with Flow-Sat-Prep Co-authors: Naoyuki Takei, Hiroyuki Kabasawa

66

Mochizuki, Teruhito 9.6 Assessment of Myocardial Perfusion --- Comparison of CT, MR and NM --- Co-authors: Kurata A, Kido T, Kido T, Higashino H, Hosokawa S, Kikuchi K, Miki H, Okayama H, Higaki J, Murase K.

86

Mostardi, Petrice 10.7 High Temporal and Spatial Resolution Abdominal CE-MRA Co-authors: J.F. Glockner, S. J. Riederer

95

N Natsuaki, Yutaka 9.8 A Novel Approach to ECG-Gated High Resolution Contrast-Enhanced MR Angiography in a Single Breath Hold Co-authors: J. Paul Finn, Randall Kroeker, Gerhard Laub

88

Newman, Tiffany P6. Magnetic Resonance Lymphangiography for the preoperative assessment of upper extremity lymphedema Co-authors: Julie Vasile, Joshua Levine, David Greenspun, Robert J. Allen, A.P.M.C, F.A.C.S II, Kemi Babagbemi, Martin R. Prince

117


O Oh, Seung-Taek P7. Effect of stellate ganglion block on cerebrovascular system: MRA study Co-authors: Chang-Ki Kang, Dong-Yeon Kim, Young-Bo Kim, Zang-Hee Cho

118

Oshinski, John N. 9.5 Coronary Vein Motion in Patients Undergoing Cardiac Resynchronization Therapy: Implications for MR Coronary Venography Co-authors: Pierre Watson, Jonathan Suever

85

Ota, Hideki 12.4 Sex Differences of High-Risk Carotid Atherosclerotic Plaque Along with Different Levels of Stenosis – in vivo 3.0T MRI study Co-authors: Mathew J. Reeves, David C. Zhu, Michael J. Potchen, Arshad Majid, Alonso Collar, FACS, Chun Yuan, J. Kevin DeMarco

107

Özda, Emre 6.1 XIP Software Suite for XFM (X-Ray Fused with MRI) Co-authors: Abdülkadir Yazıcı, Cengizhan Öztürk

62

P Papini, Giacomo DE 12.7 Evaluation of Inflammatory Status of Atherosclerotic Carotid Plaque before Thromboendarterectomy using Delayed Contrast-enhanced Subtracted images after Magnetic Resonance Angiography Co-authors: Giovanni Di Leo, Stefania Tritella, Giovanni Nano

110

Park, Chan-A 11.1 3D Visualization of the lenticulostriate artery and the correlated infarct Co-authors: Chang-Ki Kang, Stefan Wörz, Karl Rohr, Young-Bo Kim, Zang-Hee Cho

98

Parker, Dennis 7.1 Unlocked Motion in Turbo Spin Echo of the Cervical Carotid Artery Co-authors: Jason Mendes, Jordan Hulet, Scott McNally, Seong-Eun Kim, John Roberts, Jerry Treiman

65

Q Quick, Harald P12. Towards Real-Time MR-Guided Transarterial Aortic Valve Implantation (TAVI) Co-authors: Philipp Kahlert, Holger Eggebrecht, Gernot M. Kaiser, Nina Parohl, Juliane Albert, Ian McDougall, Raimund Erbel, Mark E. Ladd

123

R Roditi, Giles 5.6 MultiMRA - Initial Experience of Single Dose Gadobenate dimeglumine for Compre-hensive MR Angiography of the Lower Limbs with Dynamic Calf, 3 Station Bolus Chase & High-Resolution Extended Phase Imaging Co-authors: S.Chandramohan

58

Ryu, Chang-Woo 11.5 High Resolution Vessel Wall MRI of the Chronic Unilateral Middle Cerebral Artery Occlusion Co-authors: Geon-Ho Jahng, Eui-Jong Kim, Woo-Suk Choi

102


S Saloner, David 4.5 Velocity Fields In Intracranial Aneurysms Co-authors: Gabriel Acevedo-Bolton, Vitaliy Rayz, Monica Sigovan, Loic Boussel, Alastair Martin, Vibhas Deshpande, Gerhard Laub

50

Saranathan, Manojkumar 10.4 Breath-held non-contrast enhanced MR angiography with a novel group- encoded k-space segmentation method Co-authors: Pauline W Worters, and Shreyas Vasanawala

92

Sheng, Rubin 1.5 Low Dose (0.1 mmol/kg) Gadodiamide-Enhanced Magnetic Resonance Angiography (MRA) for Detection of Renal Artery or Aortoiliac Occlusive Disease: Results of Two Multicenter, Prospective International Trials

28

Spincemaille, Pascal 10.8 Respiratory Gated Contrast-Enhanced MRA of the Liver Co-authors: Martin R Prince, Yi Wang

96

Stalder, Aurelien F. 3.5 Analysis of swirling flow patterns using 4D flow-sensitive MRI Co-authors: A. Frydrychowicz, A. Harloff, Q. Yang, J. Hennig, K. C. Li, M. Markl

42

T Takehara, Yasuo 3.1 Hemodynamic Assessment of Abdominal Aortic Aneurysm with Use of Three Dimensional Cine Phase Contrast Image and Flow Analysis Application Co-authors: Haruo Isoda, Hiroyasu Takeda, Marcus Alley, Roland Bammer, Takashi Kosugi, Toshiyuki Shimizu, Masaya Hirano, Tetsuya Wakayama, Naoki Unno, Norihiko Shiiya, Harumi Sakahara

38

U Unal, Orhan 6.2 Multi-baseline PRF-based Thermometry for MR-guided Interventions using an Extensible Real-Time Platform Co-authors: Peng Wang

63

V Vakil, Parmede 10.2 Combined Renal MRA and Perfusion with a Single Dose of Contrast Co-authors: Hyun J. Jeong, Parmede Vakil, James C. Carr, Timothy J. Carroll 11.2 High Resolution 2D Radial FLASH MR DSA for Intracranial Vascular Disease Co-authors: M. Hurley, H. Batjer, B. Bendok, C. Eddleman, T. Carroll

90

99

Velikina, Julia 8.3 A New Compressed Sensing and Magnitude Constraint Based Approach to Acceleration of Phase Contrast Velocimetry Co-authors: Kevin Johnson, Alexey Samsonov

76

Versluis, Bas 1.3 DCE MRI with Gadofosveset in Peripheral Arterial Disease: Assessment of the Hyperemic Microvascular blood volume Co-authors: Patty J. Nelemans, Joachim E. Wildberger, Walter H. Backes, Tim Leiner

26


W Wang, Yi 7.5 Quantitative Susceptibility Mapping of Intracerebral Hemorrhage Co-authors: Tian Liu, Deqi Cui, Liuquan Cheng, Min Lou, Jianzhong Zhang, Minming Zhang

69

Wang, Kang 2.3 Dynamic Pulmonary Perfusion Imaging using Interleaved Variable Density Sampling, Parallel Imaging and Cartesian HYPR Reconstruction Co-authors: F.R. Korosec, N.S. Artz, M.L. Schiebler, C.J. Francois, S.B. Reeder, T.M. Grist, R.F. Busse, J.H. Holmes, S.B. Fain, S.K. Nagle 8.5 3D Time-Resolved MRA of Lower Extremities using Interleaved Variable Density Sampling, Parallel Imaging and Cartesian HYPR Reconstruction Co-authors: J. Holmes,R. Busse, P. Beatty, J. Brittain, C. Francois, S. Reeder, L. Keith, Y. Wu, F. Korosec

31

78

Weckbach,Sabine P8. Dynamic 3D MR Angiography for the Assessment of Rheumatoid Disease of the Hand Co-authors: Mike Notohamiprodjo, Christian Glaser, Hans Hatz, Maximilian Reiser

32

Willinek, Winfried A. 2.4 Preoperative mapping of autogenous saphenous veins as an imaging adjunct to peripheral MR angiography in patients with PAOD and femorodistal bypass grafting: Prospective comparison with ultrasound and intraoperative findings Co-authors: Jah-Kabba AM, Kukuk GM, Hadizadeh DR, Koscielny A, Verrel F, Schild HH

94

Worters, Pauline W 10.6 Improved signal in inflow-sensitive bSSFP MRA using variable flip angles Co-authors: Brian A Hargreaves

80

Wu, Yijing 8.7 HYPR CE: High resolution 4D contrast enhanced MRA using single dose, dual injection and constrained reconstruction Co-authors: Kevin Johnson, Steven Kecskemeti, Charles Mistretta, Patrick Turski

31

Y Yang, Qi 9.2 Integrating High Spatial-Resolution, 3D Whole-Heart Viability Imaging and Coronary MRA at 3 Tesla Co-authors: Kuncheng Li, Xiaoming Bi, Feng Huang, Renate Jerecic, and Debiao Li

82

Yang, Dalmo P9. Time-Resolved MR Angiography for Detecting and Grading Ovarian Venous Reflux: Comparison with Conventional Venography Co-authors: Hyun Cheol Kim, Geon-Ho Jahng

120

Yerly, Jerome 8.2 Accelerating 3D TOF with Compressed Sensing Co-authors: M. L. Lauzon, Robert J Sevick, R. Frayne

75

Young, Phillip M. 5.9 Comparison of CAPR MRA with CT Angiography for Evaluation of Below the Knee Runoff:Preliminary Results Co-authors: James F. Glockner, Terri J. Vrtiska, Thanila Macedo, Clifton R. Haider, Petrice M. Mostardi, Stephen J. Riederer

61


Z Zhang, Honglei 10.1 Comparison of Renal MRA/CTA and Angiography Data in CORAL Study Co-authors: Matsumoto A, Cutlip D, Murphy TP, Cooper C, Dworkin L, Prince MR

89

Zheng, Jie 12.6 Atherosclerotic Plaque Imaging with SWI Approach Co-authors: Alexandros Flaris, David Muccigrosso, Adil Bashir

109

Zou, Zhitong 1.2 Comparison of Blood-Pool and Extracellular Contrast Agents on MRA of Abdominal Perforator Flap Arteries Co-authors: Michelle Cerilles, David T Greenspun, Joshua L Levine, Julia Vasile, Constance Chen, Christine Ahn, Martin R Prince.

25


Notes

dear friends and participants of the 2010 mr angio club meeting

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