clinical application and protocols: cardiovascular ... · clinical application and protocols:...
TRANSCRIPT
22/10/62
1
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Clinical application and Protocols: Cardiovascular vascular imaging.
Saifhon Admontree
B.Sc.(Radiological Technology) Mahidol University
M.Sc.(Medical Imaging) Chulalongkorn University
AIMC, Ramathibodi Hospital
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Disclosure This presentation slide supported by Bayer Thai
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
3
Patient preparation in Cardiac CTA Cardiac CT Angiography technology Contrast protocols and timing Image Reconstruction Protocols Dual Energy CT applications in Cardiac CTA Radiation dose considerations in Cardiac CTA
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Patient Preparation Protocol
Patient safety
Allergy (anaphylaxis)
Renal insufficiency
Claustrophobia
Pregnancy
Image quality
Metallic artefacts
Motion artefacts
Breath hold
Gregory Kicska. Patient preparation and coronary CTA techniques. pdf. Aviable from; http://www.nasci.org/Portals/4/Meetings/RSSA/Cardiac/CTA/2013/Kicska.pdf
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
• งดอาหาร และเครองดมทกระตนการท างานของหวใจ เชน ชา กาแฟ อยางนอย 4-6 ชวโมง
• กนยาลดการเตนของหวใจ พจารณาโดยรงสแพทยและแพทยเจาของไข
• สวมใสเสอผาทสบายและเชดท าความสะอาดบรเวณทตด electrode
• หลกเลยงการตด electrode ต าแหนงกระดก เพราะจะกนสญญาณคลนไฟฟาหวใจสงผลใหกราฟของelectrocardiogram ไมชดเจน
การจดทาผปวย
• ผปวยนอนหงายราบกบเตยง ชแขนขนเหนอศรษะ ในทาทสบาย
• จดผปวยใหอยกงกลางต าแหนง Iso-center
• ฝกซอมผปวยใหกลนใจนงทสด
• บรรเทาความวตกกงวลของผปวย
• ฉดสารละลายน าเกลอเพอทดสอบหลอดเลอด กอนการฉดสารทบรงส
• วางเสอตะกวเพอปองกนอนตรายของรงสตออวยวะสบพนธ (Gonad Shielding) ในผปวยวยเจรญพนธทกครง
เตรยมตวกอนตรวจ
Preparation: 24-1 hr pre-exam
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Cardiac CT Angiography technology
Review of Radiology Physics: A Handbook for Teachers and Students - 1.1.1 Slide 1
Dual Energy CT scanners
22/10/62
2
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
16-row MDCT (A) 64-row MDCT (B) 320-row MDCT (C)
Example illustrating the improved depiction of distal coronary artery branches (white arrows) using 64-row (Panel B ) and 320-row CT (Panel C) in a 58-year-old female patient.
M. Dewey, Cardiac CT, DOI 10.1007/978-3-642-41883-9_6, © Springer-Verlag Berlin Heidelberg 2014
Technical Requirements for Cardiac CTA: CT scanner with at least
64 simultaneous rows.
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Wide beam (320-detector row) CT scanner
160mm in z-coverage
(320x0.5mm)
Enable volumetric imaging
within one cardiac cycle.
Short rotation time of 0.35s.
320- detector row CT scanner
specifications:
Cardiac CT Angiography technology (Cont’d)
Technical Aspects of Cardiac CT: Improving Speed of volume coverage.
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land Cardiac CT Angiography technology (Cont’d)
160mm z-coverage (320-MDCT)
Entire heart can be captured in
single heartbeat.
Eliminate Stair-Step and
Misalignment Artifacts
Increase temporal resolution
Wide beam (320-detector row) CT scanner
Advantages of 320- detector row CT in
cardiovascular imaging;
Technical Aspects of Cardiac CT: Improving Speed of volume coverage.
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Technical Aspects of Cardiac CT: Improving spatial resolution.
Optimise pixel size (pixel size = FOV/ matrix)
Cardiac CT Angiography technology (Cont’d)
S. Edyvean. Technical Aspects of Cardiac CT.ppt.
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Effect of the reconstruction fi eld of view on the image quality of coronary artery reconstructions. Threedimensional reconstructions of the LAD show the relevantly lower spatial resolution obtained using
the 320-mm reconstruction field of view ( Panel A ), when compared with the smaller 180-mm reconstruction field of view ( Panel B ), as illustrated by the mid-LAD ( arrow ) and the first diagonal branch
( arrowhead ). M. Dewey, Cardiac CT, DOI 10.1007/978-3-642-41883-9_6, © Springer-Verlag Berlin Heidelberg 2014
FOV 320mm FOV 180mm
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land Coronary CT angiography Technique (cont’d)
Bruce Precious. Protocols in Cardiac CT.2016 ppt.
Technical Aspects of Cardiac CT: Improving temporal resolution.
22/10/62
3
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Ibrahim Danad, Zahi A. Fayad, Martin J. Willemink, James K. Min. New Application of Cardiac CT. JACC: CARDIOVASCULAR IMAGING. 2015 June; 8(6):710–23.
The principles of DECT are based largely on;
Photoelectric effect and can be achieved by exploiting the
energy dependent attenuation of materials
Enables distinct differentiation between 2 basis materials,
based on dissimilar tissue characteristics with respect to
their energy dependent x-ray attenuation.
Cardiac CT Angiography technology (Cont’d)
Technical Aspects of Cardiac CT: Dual Energy Computed Tomography
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Dual source scanner (a): two x-ray sources, which are operated at different energies.
Figure 1. a–d. Illustration showing different types of dual energy CT scanners.
Dual spin technology (c): using a volume scanner, the patient is initially scanned at one energy level (135 kVp) and immediately scanned in the same anatomic location using a different energy level (80 kVp).
Dual layer/ spectral detector CT (SDCT) (d):
Rapid kVp switching (b): each x-ray projection, kVp is rapidly switched between low (80 kVp) and high energy (140 kVp) levels.
Cardiac CT Angiography technology (Cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
15
Figure 2. Dual layer or spectral detector CT (SDCT)
Single X-ray source
Cardiac CT Angiography technology (Cont’d)
Two layers of Spectral detectors CT,
Top layer (yttrium-based garnet scintillator) absorbing low energy photons,
Bottom layer(gadolinium-oxysulphide) absorbing high energy photons.
Differentiate materials of
different effective atomic numbers.
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Types of images from the detector-based spectral CT scanner
Rassouli N, Etesami M, Dhanantwari A, Rajiah P. Detector-based spectral CT with a novel dual-layer technology: principles and applications. Insights Imaging 2017;8:589-98.
Cardiac CT Angiography technology (Cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land Cardiac CT Angiography technology (Cont’d)
Dual energy CT applications in cardiovascular imaging;
Virtual monoenergetic images are useful for boosting contrast and reducing artifacts in suboptimal studies.
Rassouli N, Etesami M, Dhanantwari A, Rajiah P. Detector-based spectral CT with a novel dual-layer technology: principles and applications. Insights Imaging 2017;8:589-98.
(b) 45-keV virtual monoenergetic image (VMI) at the same level shows significant improvement in the contrast attenuation, especially in the left atrium (red arrow).
(a) Coronal 120-kVp shows poor contrast opacification of the vascular structures, particularly the left atrium (yellow arrow), due to contrast extravasation during the scanning.
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land Cardiac CT Angiography technology (Cont’d)
Dual energy CT applications in cardiovascular imaging;
Virtual monoenergetic images are useful for boosting contrast and reducing artifacts in suboptimal studies, obviating the need for a repeat contrast injection.
Prabhakar Rajiah, Suhny Abbara and Sandra Simon Halliburton. Spectral detector CT for cardiovascular applications. Diagn Interv Radiol DOI 10.5152/dir.2016.1625.
Conventional polyenergetic CT image obtained for evaluation of pulmonary
embolism with poor vascular enhancement due to contrast extravasation
Virtual 40 keV monoenergetic image shows significantly improved
enhancement permitting evaluation of the pulmonary arteries
22/10/62
4
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land Cardiac CT Angiography technology (Cont’d)
Dual energy CT applications in cardiovascular imaging; Virtual unenhanced image (c) created from spectral data obtained just after contrast injection. Like the true unenhanced image at approximately the same level, the virtual unenhanced image shows no contrast in the aorta and other vascular structures.
Prabhakar Rajiah, Suhny Abbara and Sandra Simon Halliburton. Spectral detector CT for cardiovascular applications. Diagn Interv Radiol DOI 10.5152/dir.2016.1625.
(a) True unenhanced image (b) Contrast-enhanced image (c) Virtual unenhanced image
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
20
Chandra N, Langan DA. Gemstone Detector: Dual Energy Imaging via Fast kVp Switching in Dual Energy CT in Clinical Practice. London New York: Springer Heidelberg Dordrecht 2011.
Dual energy CT applications in cardiovascular imaging;
Good agreement of virtual unenhanced images (B) and true conventional non-contrast (A) calcium scoring scans (CAC).
A B
Cardiac CT Angiography technology (Cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
21
Dual energy CT applications in cardiovascular imaging;
Reduction in calcium blooming artifact.
Cardiac CT Angiography technology (Cont’d)
Prabhakar Rajiah, Suhny Abbara and Sandra Simon Halliburton. Spectral detector CT for cardiovascular applications. Diagn Interv Radiol DOI 10.5152/dir.2016.1625.
(A) significant calcium blooming
(green) in coronary artery, with luminal area of 3.5 mm²
(A) (B)
(B) 160 keV image with reduced
blooming and better defined lumen with area of 7.4 mm².
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Basic Technical Concepts of CT Angiography:
Contrast administration – arterial opacification.
Computed Tomography – Multidetector (64MDCT)
Time scan acquisition during the arterial phase.
Cardiac CT - ECG synchronization.
Contrast protocols and timing
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
CT angiography contrast administration:
Proportional to the iodine administration rate
Iodine concentration of contrast medium
Injection flow rate (mL/s)
Injection duration (larger volume of contrast)
Contrast protocols and timing (cont’d)
Fleischmann, D. Radiol Clin N Am, 2010; 48
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Iodine concentration of contrast medium
Simulated contrast enhancement
curve of the abdominal aorta
(125 ml of contrast at 4mL/s,
three CM concentrations)
Bae KT. Radiology 2010;256:32
Higher Iodine concentration increased arterial enhancement
Contrast protocols and timing (cont’d)
22/10/62
5
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Injection flow rate (mL/s); higher flow rate of CM
Increased arterial enhancement,
Duration decreases.
Contrast protocols and timing (cont’d) Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Determine the contrast arrival time;
Bolus tracking
Timing bolus
Perform diagnostic scan near peak enhancement
achieved with the contrast bolus
in the target vessel.
CT angiography: basic strategy
Bae KT. Radiology 2010;256:32
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Scan Timing Methods;
Timing bolus
Select target location from scout topogram.
Inject small test-bolus (15 – 20 mL contrast).
Acquire low-dose dynamic scan at specified location during injection.
ROI in target structure.
Measure time-attenuation curve
Contrast material arrival time in aortic root
Contrast protocols and timing (cont’d) Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Scan Timing Methods;
Bolus Triggering (or Bolus Tracking)
Select trigger location
Acquire reference image
Place ROI in vascular structure of interest
Inject diagnostic contrast bolus in target structure
Acquire low-dose dynamic scans, monitor attenuation in ROI
Start scan when desired threshold reached Fleischmann, D. Radiol Clin N Am, 2010; 48: 237KT. Radiology 2010;256:32
Contrast protocols and timing (cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Saline chaser
Pushes contrast in tubing and peripheral veins into central veins
40 – 50 cc, allows reduction in contrast volume
Increases arterial peak attenuation
Reduced streak artifacts from veins and right heart
Simpler to implement with dual head injectors
Bae KT. Radiology 2010;256:32
Contrast protocols and timing (cont’d) Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Intermediate attenuation in right heart to minimize contrast related streak artifacts but allow visualization of right heart structures.
High right heart attenuated
Streak artifacts
Low right heart attenuated
No streak artifacts RH structures not seen
Intermediate right heart attenuated
No streak artifacts RH structures visible
Kerl JM, Radiology 2008;247(2):356
Contrast protocols and timing (cont’d)
22/10/62
6
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Use of lower voltage results in stronger contrast enhancement (such as 100 and 80 kVp results in higher CT attenuation than 120 kVp), because;
X-ray output energy at these
low voltages is closer to the
iodine k edge of 33 keV
Improve vascular and
parenchymal enhancement.
Bae KT. Radiology 2010;256:32
Contrast protocols and timing (cont’d) Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Higher contrast concentrations- higher arterial enhancement
Higher flow rate 4 – 5 mL/s
Saline chaser
Lower kVp when possible
Timing bolus or bolus tracking
CT angiography Summary points
Contrast protocols and timing (cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
M. Dewey, Cardiac CT, DOI 10.1007/978-3-642-41883-9_6, © Springer-Verlag Berlin Heidelberg 2014
Cardiac CT Angiography Protocol: Patient positioning for cardiac CT
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Start and End location
Carina to Cardiac apex.
Scan time delayed
Prospective ECG gating Technique.
Following Breath Exercise the system will automatically select the target phase.
HR ≤ 65bpm = 75%
HR > 66bpm = 40%
Cardiac CT Angiography Protocol: Calcium Scoring Technique
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Calcium Scoring
Technique;
Breath exercise
Note: ECG gating technique was used in Cardiac study.
Calcium Scoring Technique (cont’d) Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Cardiac Analysis: Calcium quantification methods
Calcium Scoring Technique (cont’d)
22/10/62
7
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Cardiac Analysis: Calcium quantification methods
Agatston volume mass score
Calcium Scoring Technique (cont’d) Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
What is Computed Tomography Angiography?
CT angiography is a type of medical exam that combines a CT scan with an injection of a contrast media to visualize arterial and venous vessels throughout the body.
Cardiac CT Angiography Protocol: Coronary CT angiography Technique
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
ECG synchronization
use data at same point in cardiac cycle to create image.
Coronary rest period = low coronary motion mid-late diastole.
Coronary CT angiography Technique (cont’d) Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Basic Principle of Cardiac CT ECG synchronization
Retrospective ECG triggering.
Prospective ECG triggering.
Coronary CT angiography Technique (cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
ECG synchronization Retrospective ECG gating –ECG dose modulation
use data at same point in cardiac cycle to create image. Beam modulated
max mA min mA
Data from entire R – R Overall dose less (40%)
max mA
min mA
Coronary CT angiography Technique (cont’d) Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
ECG synchronization Prospective ECG gating
Axial step-and-shoot, half-scan acquisition Trigger from ECG
beam completely off trigger – completely on
max mA beam on time
60 – 80% less dose
Coronary CT angiography Technique (cont’d)
22/10/62
8
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Intravenous contrast administration
Contrast volume is 1-1.1 cc per kilogram of body weight, dual head injector was used.
Based on 300-370 mgI/mL concentration.
Injection, flow rate 5-6 cc/sec plus NSS 40 cc.
Coronary CT angiography Technique (cont’d) Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Example of scanning Parameters in Coronary CTA (Toshiba CT scanner)
kVp / mA / Rotation time (sec) /Pith
100 kVp / 300-500mA or AEC/ 0.33-0.5 sec/ Pith 0.2 (Scan with overlapping pitch)
Detector collimation (mm) Helical : 0.5x80, 0.6x64,0.5x160 Axial Volume Mode: 0.5x320
Slice thickness/Interval (mm) 0.5-0.75mm/0.25-0.5mm
DFOV (mm) 180-250 mm (Small FOV)
Coronary CT angiography Technique (cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Start and End location
Carina to Cardiac apex.
Scan time delayed
Bolus tracking technique,
ROI was placed at Descending Aorta
Coronary CT angiography Technique (cont’d) Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Beyond basic CTA protocol; “Cardiac Mass” ECG gating and add delayed phase 90‐120 seconds.
Coronary CT angiography Technique (cont’d)
Standard coronary CTA protocol Delayed phase coronary CTA protocol
Bruce Precious. Protocols in Cardiac CT.2016 ppt.
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Image Reconstruction Protocols
Post-processing
techniques
1) Multiplanar Reconstruction (MPR) and MIP 2) Volume Rendering Technique (VRT) 3) Curve Reformation 4) Cardiac Function Analysis
The advent of MDCT particularly with scanners having 64 or more detectors, has continued to improve temporal resolution and allows the acquisition of “isotropic voxels”
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
• Postprocessing technique that takes the highest-attenuation voxel in a predetermined slab of data and projects it from the user toward the viewing screen, resulting in a two-dimensional image.
• Only the highest-attenuation objects, typically contrast material and bone, are preferentially displayed and retained in the image.
Maximum Intensity Projection(MIP)
Image Reconstruction Protocols (cont’d)
22/10/62
9
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Multiplanar Reconstruction (MPR)
2D Technique Used (Cardiac CTA study)
5 mm interval 2mm of axial, coronal, sagittal, RAO and LAO Maximum Intensity Projection (MIP) reconstruction.
Axial: 5 mm interval 2mm
Image Reconstruction Protocols ( Cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Multiplanar Reconstruction (MPR)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Multiplanar Reconstruction (MPR)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Multiplanar Reconstruction (MPR)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Multiplanar Reconstruction (MPR)
Image Reconstruction Protocols ( Cont’d)
2D Technique Used (Cardiac CTA study)
5 mm interval 2mm of axial, coronal Maximum Intensity Projection (MIP) reconstruction.
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Multiplanar Reconstruction (MPR)
2D Technique Used (Cardiac CTA study)
5 mm interval 2mm of axial, coronal, sagittal, RAO and LAO Maximum Intensity Projection (MIP) reconstruction.
Coronal(A) and Sagittal (B): 5 mm interval 2mm
A B
Image Reconstruction Protocols ( Cont’d)
22/10/62
10
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Multiplanar Reconstruction (MPR) and MIP
Image Reconstruction Protocols ( Cont’d)
2D Technique Used (Cardiac CTA study)
5 mm interval 2mm of LAO Maximum Intensity Projection (MIP) reconstruction
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Multiplanar Reconstruction (MPR) and MIP
Image Reconstruction Protocols ( Cont’d)
2D Technique Used
(Cardiac CTA study)
5 mm interval 2mm of a RAO Maximum Intensity Projection (MIP) reconstruction.
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Image Reconstruction Protocols ( Cont’d)
2D Technique Used (Cardiac CTA study)
5 mm interval 2mm of a Short Axis Maximum Intensity Projection (MIP) reconstruction
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Multiplanar Reconstruction (MPR)
2D Technique Used (Cardiac CTA study)
-Short Axis, -2,3 or 4 Chamber Views reconstruction.
Short Axis (MIP): 5 mm interval 2mm
Image Reconstruction Protocols ( Cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Image Reconstruction Protocols ( Cont’d)
2D Technique Used
(Cardiac CTA study)
5 mm interval 2mm of a Short Axis Maximum Intensity Projection (MIP) reconstruction
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Multiplanar Reconstruction (MPR)
2D Technique Used (Cardiac CTA study)
-Short Axis, -2,3 or 4 Chamber Views reconstruction.
2 CH views reconstruction
Image Reconstruction Protocols ( Cont’d)
22/10/62
11
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Multiplanar Reconstruction (MPR)
2D Technique Used (Cardiac CTA study)
-Short Axis, -2,3 or 4 Chamber Views reconstruction.
4 CH views reconstruction
Image Reconstruction Protocols ( Cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Image Reconstruction Protocols ( Cont’d)
2D Technique Used (Cardiac CTA study)
5 mm interval 2mm of a 3 chamber view, Maximum Intensity Projection (MIP) reconstruction
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Multiplanar Reconstruction (MPR)
2D Technique Used (Cardiac CTA study)
-Short Axis, -2,3 or 4 Chamber Views reconstruction.
3 CH views reconstruction
Image Reconstruction Protocols ( Cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
3D Reconstruction: Volume Rendering (VR)
Image Reconstruction Protocols (cont’d)
• 3D technique in which the CT attenuation values for each voxel can be assigned a specific color,
• Provides the depth and spatial information and
• Facilitate surface evaluation of the heart and coronary arteries.
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
3D Technique Used VR Projection/3D rendering
Image Reconstruction Protocols ( Cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
• Because normal coronary arteries are often tortuous, accurate evaluation requires assessment of the entire vessel along its center line.
• Curved reformatted images provide this capability by sampling a given volume (ie, artery) along a predefined curved anatomic plane.
Curved Reformation
Image Reconstruction Protocols (cont’d)
22/10/62
12
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
2D Technique Used (Cardiac CTA study)
Curve reformat of coronary artery vessel (RCA, LAD,LCX).
LAD LAD
LCX LCX
Curve Reformation
Image Reconstruction Protocols (cont’d) Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Workstation with automatic curved multiplanar reformation and three-dimensional data segmentation and analysis capabilities.
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Cardiac Analysis: Cardiac Function Analysis
Image Reconstruction Protocols ( Cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Cardiac Analysis: Cardiac Function Analysis
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
The 17-segment model was recommend using for reporting myocardial segment.
Cardiac Analysis:
Myocardium Analysis
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Cardiac Analysis:
Myocardium Analysis
22/10/62
13
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land Cardiac Analysis:
TAVI (Transcatheter Aortic Valve Implantation) protocol
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Radiation Dose consideration in Cardiac CTA
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
76 CTDIvol and DLP displayed on monitor are based on 32-cm body phantom.
Conversion factor (k= 0.014 mSv/mGy.cm) was applied to estimate the effective dose (E) from dose length product (DLP).
Mean ± SD values and the third quartile or 75th percentile of CTDIvol, DLP and effective
dose of coronary calcium scoring and cardiac CTA in retrospective ECG- gating technique.
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
77
Wide beam detector (320-MDCT) 64-MDCT
Volumetric imaging of whole heart and coronary vessels can be imaged within single heartbeat
Mean effective dose range from 4.4 to 7.2 mSv.
Several heartbeats were acquired to capture the entire heart leading to high radiation dose
Mean effective dose range from 4.1 to 20.0 mSv.
The mean Effective Dose (E) in Cardiac CT Angiography from literature review
Radiation Dose consideration in Cardiac CTA ( Cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
78
The patient dose reduction in Cardiac CTA should be considered by means of ;
1) Rigorous scan coverage fit to the heart or according to the clinical consideration.
2) Tube voltage reduction to increase the photoelectric effect of contrast medium and tissue.
3) Use iterative reconstruction algorithm. 4) Anatomical tube current modulation. 5) ECG- tube current modulation and prospectively triggered CT
angiography in case of stable low heart rate. 6) DRLs was used as the optimization tool to reduce the radiation
dose, while as maintain acceptably level of image quality.
Radiation Dose consideration in Cardiac CTA ( Cont’d)
22/10/62
14
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
79
The patient dose reduction in Cardiac CTA should be considered by means of ; ECG- tube current modulation.
Radiation Dose consideration in Cardiac CTA ( Cont’d)
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
80
The patient dose reduction in Cardiac CTA should be considered by means of ; prospectively triggered CT angiography in case of stable low heart rate.
Radiation Dose consideration in Cardiac CTA ( Cont’d)
% 50
RR-interval
ECG-triggered tube modulation
Continuous scanning
Prospective ECG-triggering
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
Image noise reduction on axial images cardiac CT reconstructed with adaptive iterative reconstruction (Panel B ) in comparison to standard filtered back projection (Panel A ).
(Images courtesy of Kazuhiro Katada, Fujity University)
M. Dewey, Cardiac CT, DOI 10.1007/978-3-642-41883-9_6, © Springer-Verlag Berlin Heidelberg 2014
The patient dose reduction in Cardiac CTA should be considered by means of ; iterative reconstruction .
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
1. Ibrahim Danad, Zahi A. Fayad, Martin J. Willemink, James K. Min. New Application of Cardiac CT. JACC: CARDIOVASCULAR IMAGING, VOL. 8, NO. 6, JUNE 2015:710–23.
2. CT Coronary Angiography: 256-Slice and 320-Detector Row Scanners.
3. Wang M, Qi HT, Wang XM, Wang T, Chen JH, Liu C. Dose performance and image quality: dual source CT versus single source CT in cardiac CT angiography. Eur J Radiol. 2009; 72:396–400.[PubMed: 18835119]
4. Atif Khan, Faisal Khosa, Khurram Nasir, Aya Yassin, and Melvin E. Clouse. Comparison of Radiation Dose and Image Quality: 320-MDCT Versus 64-MDCT Coronary Angiography. AJR Am J Roentgenol. 2011 July ; 197(1): 163–168.
5. Prabhakar Rajiah, Suhny Abbara and Sandra Simon Halliburton. Spectral detector CT for cardiovascular applications. Diagn Interv Radiol DOI 10.5152/dir.2016.1625.
6. Baumller et al. Dual-Source versus 64-Section CT Coronary Angiography at Lower Heart Rates: Comparison of Accuracy and Radiation Dose. Radiology: Volume 253: Number 1—October 2009.
7. J Rixe, G Conradi, A Rolf, A Schmermund, A Magedanz, et al. Radiation dose exposure of computed tomography coronary angiography: comparison of dual-source, 16-slice and 64. BMJ: / Volume 95.
82
Faculty of Medicine Ramathibodi Hospital Mahidol University: Wisdom of the Land
8. Hirai, J. Horiguchi, C. Fujioka, M. Kiguchi. Prospective versus Retrospective ECG-gated 64-Detector Coronary CT Angiography: Assessment of Image Quality, Stenosis, and Radiation Dose. Radiology: Volume 248: Number 2—August 2008.
9. Frank J. Rybicki, Hansel J. Otero, Michael L. Steigner, Gabriel Vorobiof et al. Initial evaluation of coronary images from 320-detector row computed tomography. Int J Cardiovasc Imaging (2008) 24:535–546.
10. Dianna M.E. Bardo* and Paul Brown. Cardiac Multidetector Computed Tomography: Basic Physics of Image
11. Acquisition and Clinical Applications. Current Cardiology Reviews, 2008, Vol. 4, No. 3.
12. Gregory Kicska. Patient preparation and coronary CTA techniques. pdf. Aviable from;http://www.nasci.org/Portals/4/Meetings/RSSA/Cardiac/CTA/2013/Kicska.pdf. Access: 6 March 2018.
13. Cardiac and CT angiography techniques Cardiovascular Boot Camp. NASCI 40th Annual Meeting October 13, 2011.
14. Kyongtae T. Bae. Intravenous Contrast Medium Administration and Scan Timing at CT: Considerations and Approaches. Radiology 2010;256:32-61.
15. Rassouli N, Etesami M, Dhanantwari A, Rajiah P. Detector-based spectral CT with a novel dual-layer technology: principles and applications. Insights Imaging 2017;8:589-98
83