introduction to update 2005 advanced ultrasound imaging ... · advanced ultrasound imaging...

Introduction toadvanced Ultrasound Imaging techniquesIntroduction toIntroduction toadvanced Ultrasound Imaging techniquesadvanced Ultrasound Imaging techniques

Christian Kollmann Ph.D

Center for Biomedical Engineering & Physics

Medical University of Vienna

Technical Ultrasound-Lab at the General Hospital

(AKH Vienna)Level 4L, Waehringer Guertel 18 – 20A - 1090 Vienna

Tel : (+43 1) 40400 - 1712Fax: (+43 1) 40400 - 3988

E-mail : christian.kollmann@meduniwien.ac.atInternet : www.bmtp.akh-wien.ac.at/people/kollch1/

update 2005

UltraSoundUltraSound--LabLab

1. IntroductionWhen clinical imaging began … & its actual clinical diversity

2. Modern Equipment technologies & its clinical applications2.1 advanced signal processing developments

- Multi-Hertz & Fusion Imaging- SonoCT, Panoramic View, B-Flow- Coded pulse excitation- Multimodal Imaging- Harmonic Imaging (with / without contrast agents)- Elastography- 3D- / 4D-mode

2.2 advanced Hardware developments- Matrix transducer design- portable & wire-less US equipment (ASICS technology)

Table of contents

Clinical A-Mode (historical medical measurements, early 50s)

The austrian physician Dussik was the first (1942), who has used ultrasound formedical-diagnostic purposes

Transmission mode (Hyperphonometry)on the head

(shown a later measurement session)

left righthead side

Development of clinical imaging applications

year # of applications

advancedsignal processingdevelopments

advancedadvancedsignal processingsignal processingdevelopmentsdevelopments

Requirements :• piezoelectric materials with large bandwidth• complex transducer (128 elements)• selectable frequencies, e.g. 2-3 (“Multi-Hertz”)

selectable spectra of probe

Fusion Imaging :• combination of generated high- &

low-frequency 2D-images

Advantages :• fine structured images• higher contrast resolution• larger penetration depth with

same probe

Modern Equipment technology : Multi-Hertz & Fusion Imaging

bandwidth of probe

- propagation of scanlines in different angles- acquiring of images from slight different views

combining all acquired images to one image in real-time

SonoCT, ATLSieClear, Siemens

Signal processing technique (SonoCT)UltraSoundUltraSound--LabLab

Clinical applications of US imaging techniques (SonoCT)

Abdomen

conventional new techniqueSonoCT, ATLSieClear, Siemens

conventional new techniquepositioning of a biopsy needle

Clinical applications of US imaging techniques (SonoCT)UltraSoundUltraSound--LabLab

ATL / Philips

Abdominal & Organs

• emergency diagnosis• tumors, lesions• tissue differentiation• shape- & dimension evaluation

Clinical applications of US imaging techniques (bowel)UltraSoundUltraSound--LabLab

7 cm long breast abcessssurvey of extremities

• large field scanning• pixel-by-pixel pattern recognition technique

B - Mode(Siemens)

Clinical applications of US imaging techniques (SieScape)

complete fetustotal liver scanning

B - Mode(General Electric)

Clinical applications of US imaging techniques

Visualization of blood flow within B-mode without Doppler shift-evaluation

B-mode / B-Flow (General Electric, SieFlow, Siemens)

• simultaneous imaging of tissue & blood flow• high resolution images at high frame rates

• emission of a coded broadband pulse (coded excitation)• signal tissue typically 20 – 30 db > signal reflected by blood

• echos are cross-correlated• echos available, that are equal to coded ones• amplitude of echos is enhanced• echo has its original short pulse characteristics

technical implementation :• 2 resp. 4 pulse sequences / image line (10 - 12 for CFM)• echos of tissue (stationary) -> B-mode black-coded• echos of blood or dyn. tissue -> B-mode grey-coded

1 1 1 0 1 0 1 1

Features :

• direction & velocity cannot be originally quantified• signal amplitude depends on n, D-blood• small angle dependency• representation of scatters depend on scanner´s line generation• artefacts by moving tissue• higher spatial- & time resolution than CFM• higher frame rate (19 Hz instead of 8 Hz CFM)• no flow information behind calcifications

B-mode / B-Flow (General Electric) II

Artery carotis

Clinical applications of B-Flow

conventional color Doppler B-Flow

Internal carotis artery stenosisCommon carotid

(B-flow color-coded)

Clinical applications of B-Flow II

dialysis graftpseudoaneurysm

Common carotis(ulceration)

Clinical applications of B-Flow III

UltraSoundUltraSound--LabLabModern Equipment technology : Coded pulse excitation

• Codes are a unique signature on the sound beamformed by repeating a specific pattern of 1’s and 0’s

• Codes may be used to- Improve sensitivity (e.g. Coded Excitation)- Suppress unwanted signal components

• Applications in - B-flow - coded Harmonics - coded Harmonic Angio

1 1 1 0 1 0 1 1

conventional pulse coded pulse train

UltraSoundUltraSound--LabLabModern Equipment technology : Coded pulse excitation II

• 7 MHz resolution at penetrations up to 20 cm (shown : phantom study)

18 cm18 cm

?conventional coded excitation

UltraSoundUltraSound--LabLabModern Equipment technology : Coded pulse excitation III

duodenum

combiningdifferent imagingmodalitiesto one image(fusion/matching)

homogenous 4 x 4Transformationmatrix T

original2-D images

matched2-D image

co-registrationprocess

Clinical applications of Multimodal Imaging (Matching)

CT, MRI

UltraSound-Lab BMTP, Vienna

Clinical applications of Multimodal Imaging (Matching) II

- additional membrane is visible (arrow)

Subarachnoidal cyst (TCCS & MRT)

- additional flow information is available

- circulus arteriosus Willisii within thebenign tumor visible

- information about location for pre-operational plannings

- therapy control easily & with an inex-pensive modality possible

Meningeom (TCCS & CCT)

Clinical applications of Multimodal Imaging (Matching) IIIUltraSoundUltraSound--LabLab

UltraSoundUltraSound--LabLabModern Equipment technology : Harmonic imaging (static)

• using non-linear parts of the echo (i.e. higher frequencies)for imaging process

• US propagation through tissue results in non-linear effects :

harmonics

conventional

Applications known e.g. as : Tissue Harmonic Imaging(THI, Siemens)

freceive = femit

freceive = femit + 2 femit + 3 femit

emission receive receive

narrow band

Clinical applications of Harmonic Imaging

normal Tissue Harmonic Imaging(Siemens)

normal Tissue Harmonic Imaging

thrombus and ovarian cyst

Clinical applications of Harmonic Imaging II

Tissue Harmonic Imaging (right, Toshiba)4-chamber view

Tissue Doppler (Harmonic) Imaging TDI combined with M-modeheart systolic / diastolic(left /right) (Toshiba)

Clinical applications of Harmonic Imaging III

UltraSoundUltraSound--LabLabModern Equipment technology : Harmonic imaging (dynamic)

• in combination with US contrast agents (UCA) also non-linear partsof the echo (i.e. higher frequencies) can be used for imaging

n : harmonic number (½, 1,2,..)v : velocity scattererc : sound speedα : Doppler angle

Applications knowne.g. as :Second Harmonic,Intermittent HarmonicImaging

cvfnf emit

ndαcos2

UltraSoundUltraSound--LabLabModern Equipment technology : Harmonic imaging (dynamic) II

from : Kollmann, Putzer, Radiologe 6 (2005)

UltraSoundUltraSound--LabLabModern Equipment technology : Harmonic imaging (dynamic) III

from : Kollmann, Putzer, Radiologe 6 (2005)

UltraSoundUltraSound--LabLabModern Equipment technology : Harmonic imaging (dynamic) IV

• wide bandwidth probe

• sophisticated filter algorithm

selectable tissue or CA display

conventional

freceive = femit

Normal perfusion of the myocardiumusing Levovist as contrast Agent (destroying CA phase)

(Toshiba)

(Intermittent / Flash echo)

Clinical images in combination with ultrasound contrast agents :

allows imaging of smalll amounts of UCAwith high spatial resolution

Clinical applications of Harmonic Imaging II

UltraSoundUltraSound--LabLabModern Equipment technology : Pulse inversion Harmonics

• suppressing unwanted fundamental tissue signals

fundamental signal fundamental signal

harmonicsignal

180° phase-shiftedfundamental signal

conventional

pulse inversion

Result :

fundamental & 180° phase-shifted signalextinguish each other

only harmonic signalremains

fundamental signal

harmonic signal

180° phase-shiftedfundamental signal

Modern Equipment technology : Pulse inversion Harmonics II

harmonic signal remains

Elastography : visualization of the elastic properties of tissuesince 1991

(Elasticity- / Young-Modul)

ρ = density

c = sound speed

Z = impedance

US-Imaging : visualization of different acoustical impedancesconventional (compression, density)

(Compressibility-Modul)

Modern Equipment technology : Elastography

cZ== ρ2c K

instead of : σ = tension

ε = expansion

Acquisitionof images

(step-wise decompressionof tissue)

calculation of2D-moving matrix“ optical flow-principle”

correction ofbasis data

“ local companding “

calculation of expansion

tissue : high elasticity -> strong expansion (red coded)intrusion : low elasticity -> low expansion (blue/green coded)

Modern Equipment technology : Elastography II

phantom study for detecting structures invisible with conventional imaging

Clinical applications of Elastography

breast lesion

Clinical applications of Elastography

kidney tissue

- internal stepper motor changes the scanplane inside the transducer (KretzTechnik, A)

- the scanned volume has a pyramidalform that can be visualized in arbitraryangles

- a special “niche” mode can be displayedthat allows the observer to cut arbitrary planes within this volume and that are perpendicular to each other (90°)

3D / 4D-Mode

- a positioning device is attachedon a normal 2D-US probe/ trans-ducer

- the probe is moved “freehand” along the observed patient´s region

- the 2D-US images and the trak-king information is used tocalculate a volume image

3D / 4D-Mode “ free-hand procedure “

these technique is used for :

- displaying & measuring volumes, angles& distances

- displaying organ or skin surfaces(render mode)

Clinical applications of 3D

-3D-representation of kidney perfusion(Power Mode)

- fetal skeleton

- flow of umbilical cord

fetal gender -

- fetal fingers

Comparison -3D-US / newborn (lip cleft)

frighting fetus -

maldeformation & disorders

Clinical applications of 3D II

Clinical imaging applications (4D-Mode)

- real-time (16 fps) display of 3D-rendered fetal shape

(Kretz Technik)

3-Scape, Siemens

advancedHardware developmentsadvancedadvancedHardware Hardware developmentsdevelopments

Technical development of the 2D-Array :

• 1 D-array : discrete aperture + statical focus• 1,25 D-array : discrete aperture variation + statical focus• 1,5 D-array : dyn. aperture variation + dyn. (but symmetr.) focus• 1,75 D-array : dyn. aperture variation + dyn. asymmetr. focus• 2 D-array : dyn. aperture variation + dyn. focus

ASIC-Technology (length of element : 200 - 300 µm quadrat.; line widths 25 µm /

vias : 50 µm)

Hardware developments : Matrix transducer design

Advantage & possibilities :

• reduction of partial volume orslice-thickness effects

• higher frame rate• dynamic focussing and receiving• better image quality

• Real-Time 3D-representation (18-40 frames/sec)(“ 4D- Ultrasound “)

Hardware developments : Matrix transducer design II

Problems (some still unresolved) :

• high element density• large number of cables (> 10000)• Piezomaterial (lead zirconate / PZN-PT; multi-layer or. single crystal)• frequencies > 15 MHz (i. use between 1 - 7 MHz)• insertion loss : 60 - 70 dB above conventional array

future :fully digital probe

Hardware developments : Matrix transducer design III

Features :

• notebook-dimension• 5 - 6.4 inch TFT non-interlaced (640 x 480)• high resolution 2D (full digital beamforming)• Cine & Zoom; Caliper tools• 2D / Color (Power) Doppler• div. 2 - 7 MHz Array- probes• DR : <= 140 dB; FR : 100 frames/sec

Hardware development : Portable & wire-less US equipment

Technology :

• 4 ASICs on a board(Application-Specific Integrated Circuit1 cm2, “systems-on-a-chip”)

• dimension of transistor < 1 µm• high performance & fully digital• battery-powered• rel. low-manufacturing costs

• image storing > 50 frames

• Price : ca. 2500.- US$

Micros Q.V.(Carolina Medical, USA)

Examples :

Terason 2000(TeraTech Corp., USA)

Hardware development : Portable & wire-less US equipment II

Sonosite 180(Sonosite/ATL, USA)

Mysono 201(Medison, Korea)

Examples :

Hardware development : Portable & wire-less US equipment III

Vivid i(General Electric, USA)

Examples :

Hardware development : Portable & wire-less US equipment IV

Logiq Book XP(General Electric, USA)

depends on clinical application :

Clinical used transducer types for imaging

vaginal probe rectal probe 3D-abdominal

Transesophagealprobe

commercialpool of US

devices

Clinical available US equipmentUltraSoundUltraSound--LabLab

... and what can this be ?UltraSoundUltraSound--LabLab

ThankThank youyou forfor youryour attentionattention !!!!

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