The information contained in this presentation is proprietary and confidential Βασικές...

28
The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας στην Ελαστογραφία ShearWave. Αθήνα, 23 Ιανουαρίου 2010 Θανάσης Λούπας, PhD Principal Scientist, SUPERSONIC IMAGINE SA, France 1

Transcript of The information contained in this presentation is proprietary and confidential Βασικές...

Page 1: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Βασικές αρχές της Ελαστογραφίας.

Εξέλιξη της τεχνολογίας στην Ελαστογραφία ShearWave.

Αθήνα, 23 Ιανουαρίου 2010

Θανάσης Λούπας, PhDPrincipal Scientist,

SUPERSONIC IMAGINE SA, France

1

Page 2: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Elastography BackgroundElastography Background

2

In ancient Egypt, a link was established between

a hard mass within the human body & pathology.

In Hippocratic medicine, palpation was an essential part of a physical examination.

In the 21st century, «remote palpation» by means

of elastographic imaging is becoming a reality.

Page 3: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Young’s ModulusYoung’s Modulus

E = StressStrain

esSTRESSSTRESS

STRAINSTRAIN

kPaELASTICITYELASTICITY

High Strain Easy to deform Low ElasticityLow Strain Hard to deform High Elasticity

3

Palpation Qualitative estimation of tissue elasticity

Young’s Modulus E quantifies elasticity in units of kiloPascals, as the ratio of the Stress S (compression) applied to a body

divided by the Strain e (relative deformation) it produces.

Page 4: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Different types of soft tissue have similar density but exhibit significant variation in elasticity.

Elasticity variations can help detect / characterize focal (e.g. malignant masses) and diffuse (e.g. fibrosis) pathologies.

4

Organ / Soft tissue type Young’s modulus E (kPa)

Density (kg/L)

Breast Normal fat 18-24

1.0 ± 10% ~ water

Normal glandular 28-66

Fibrous tissue 96-244

Carcinoma 22-560

Prostate Normal anterior 55-63

Normal posterior 62-71

BPH 36-41

Carcinoma 96-241

Muscle 6-7

Liver Healthy tissue 0.4-6

Kidney Fibrous tissue 10-55

“Virtual” Biopsy“Remote” Palpation

Soft Tissue ElasticitySoft Tissue Elasticity

Page 5: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Elasticity Imaging R&DElasticity Imaging R&D

Many R& D techniques have emerged since the 1990s, based on the Ultrasound and Magnetic Resonance imaging modalities. Sonoelasticity: KJ Parker et al, 1990 Ultrasound Strain Elastography: J Ophir et al, 1991 MR Elastography: R Sinkus et al, 2000 Shear Wave Elastography: J Bercoff et al, 2004

All techniques are based on the same principle: Generate a stress, and then use an imaging technique to map the

tissue response to this stress in every point of the image.

but differ substantially in terms of their performance characteristics: Qualitative / quantitative nature, absolute / relative

quantification. Accuracy / precision / reproducibility, … Spatial / temporal resolution, sensitivity / penetration, …

COMMERCIALY AVAILABLE

5

Page 6: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

The basic principle used is the one proposed by Ophir’s group in the early 1990s:

1. Tissue compression (Stress) is induced manually by the user.

2. Multiple images are recorded using conventional imaging at standard frame rates.

3. The relative deformation (Strain) is estimated using Tissue Doppler techniques.

4. The derived strains are displayed as a qualitative elasticity image.

Initially introduced by Hitachi, and later on Siemens,

in the early 2000s.

More manufacturers have followed in the last year(s).

StrainStrain ElastographyElastography

6

Page 7: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Pre-compression RF line

Post-compression RF line

dT T

Pre-compressionRF lines

Post-compressionRF lines

Local Cross Correlation Analysis

STRAIN ESTIMATION

Strain represents relative deformation, and is expressed in qualitative units (soft / hard)

Soft objects High Strain

Hard objects Low Strain

Strain = dT / T

StrainStrain Elastography ProcessingElastography Processing

7

Page 8: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

StrainStrain Elastography SummaryElastography Summary

Straightforward implementation on current scanners (standard acquisition architecture, plus Tissue-Doppler-like processing). Stress penetration / uniformity issues. User-applied compression is attenuated by soft objects &

depth,and cannot penetrate hard-shelled lesions.

User-dependence. The extent of tissue compression affects the elasticity image.

8

Page 9: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

From Strain to Shear Wave Elastography From Strain to Shear Wave Elastography

E = Stress Strain

kPa

E = 3 cS2 kPa

Sarvazyan AP: Method and device for shear wave elasticity imaging. US Patent 5,606,971 1997.

Sarvazyan et al : Shear wave elasticity imaging -- A new ultrasonic technology of medical diagnostics. Ultrasound Med Biol 1998; 24:1419-35.

L Sandrin, S Catheline, M Tanter, C Vinçonneau, M Fink : 2D Transient Elastography Acoust. Imag., Vol. 25, pp 485-492, 2000. M Tanter, J Bercoff, L Sandrin, M Fink : Ultrafast compound imaging for 2D motion vector estimation : Application to transient elastography IEEE Trans UFFC, Vol. 49, pp 1363-1374, 2002.

9

Page 10: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Shear Waves in Medical UltrasoundShear Waves in Medical Ultrasound

Until now, Medical Ultrasound imaging has been

based entirely on Longitudinal waves.

PropagationDirection

PropagationDirection

Tissue Motion

Tissue Motion

SHEARWAVE

LONGITUDINALWAVE

10

Page 11: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Shear Wave SourcesShear Wave Sources

Natural

Heart

External

Mechanical force

Focused Ultrasound

PW Doppler

11

Page 12: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Shear Wave GenerationShear Wave Generation

Focused ultrasound is transmited at multiple points along a line of interest.

An individual Shear Wave is generated and starts propagating around each focal point.

The superposition of the individual Shear waves creates a Shear Wave-front similar to the Super Sonic Mach Cone.

SonicTouch

12

The SonicTouch Shear Wave generation process is completely automated and user-independent.

Page 13: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Shear Wave DetectionShear Wave Detection

Shear Wave Speed = 5 m/s

1 mm in 0.2 milliseconds

The typical Shear Wave speed cS in soft tissue is ~ 5 m/s.

This means that the Shear Wave needs 0.2 ms to travel 1 mm.

Thereforein order to have a spatial resolution of 1 mm, we must image the Shear Wave once every 0.2 ms, i.e. 5000 times per second.

5000 images per second needed!Almost 100 times more than the frame rates that current ultrasound scanners can offer (best case, 50-100 frames/second).

13

Page 14: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Ultrafast Imaging

Plane-wave transmissions are performed, each of them covering the whole image area.

For each transmission, the data received from all points of the image are processed using advanced reconstruction techniques to form the full image at once.

One frame is produced for every transmission, resulting in frame rates of up to 20 000 Hz.

More than one transmit events may be combined to improve image quality by trading-off some frame rate.

14

Shear Wave DetectionShear Wave Detection

Page 15: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Shear Wave Imaging StepsShear Wave Imaging Steps

Uniform-elasticityphantom

~ 100 µs

Step 1 Shear Wave generation

60 frames at a frame rate of 3000 Hz0.33 ms

Total duration: 20 ms !

Step 3 Shear Wave propagation

image formation

15

Shear Waves

Longitudinal Waves

SonicTouch

Ultrafast Imaging

Step 2 Shear Wave Detection

Page 16: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Shear Wave ElastographyShear Wave Elastography

Shear Wave Imaging sequence @ 3000Hz

Breast Elastography phantom withuniform background + hard lesion

E= 3cS2

J. Bercoff, M. Tanter, M. Fink: Supersonic shear imaging: A new technique for soft tissue elasticity mappingIEEE Trans Ultrason Ferroelectr Freq Control, pp 396-409, 2004

16

Key Reference

Shear WaveSpeed cS

Estimation

Page 17: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Shear Wave ElastographyShear Wave Elastography

Real-time operation

17

Page 18: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Shear Wave ElastographyShear Wave Elastography

Mean =5.1 kPaStdDev =0.15 kPa (3%)

Mean =10.5 kPa StdDev =0.8 kPa (7%)

10-13 Kpa

5 -7 Kpa

Calibrated Elastometer values

Accuracy / precision testing using calibrated elasticity phantoms

Shear-Wave Elastography measurements

TRULY-QUANTITATIVE NATURE• Absolute elasticity quantification• High accuracy / precision.

18

Page 19: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Shear Wave ElastographyShear Wave Elastography

TRULY-QUANTITATIVE NATURE• Absolute elasticity quantification• High accuracy / precision

19

SimulatedTissue

« Fat 1 »

« Fat 2 »

« Glandular »

« Cancer »

Reference Elasticity

(kPa)

15.8 23.9 37.4 105.7

SWE Mean (kPa)

14 20 36.4 105

SWEStdDev (kPa)

2.3 3.1 5.4 11.5

Extensive validations using calibrated tissue-mimicking phantoms.

Page 20: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Shear Wave ElastographyShear Wave Elastography

Elasticity Ratio Axial Res (mm) Lateral Res (mm)

2 1 1.1

3 1.2 1.2

10 1.3 1.1

Lateral resolution

Axial resolution

Custom-made two-layer phantomswith multiple elasticity ratios

High spatial resolution• Typically, ~ 1 mm axially & laterally for the SL 15-4 linear transducer.

20

Page 21: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Shear Wave ElastographyShear Wave Elastography

Highly-localized estimationof tissue elasticity • Especially, inside hard lesions

Phantom with liquid center inside hard lesion

Strain Elastography interprets the wholelesion as hard, because the applied manualcompression cannot penetrate the hard shell.

Shear Wave Elastography can “see” insidethe hard lesion, because the shear waves can propagate through the hard shell.

21

Page 22: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Strain vs. Shear Wave ElastographyStrain vs. Shear Wave Elastography

22

Strain Elastography tends to produce abinary classification, where the whole lesion is either hard or soft.

Shear Wave Elastography provides richer& more complex information with manycases of hard borders plus soft centers.

The differences between Strain and Shear Wave Elastography are not surprising, given the very different principles on which they are based.

Page 23: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Shear Wave Elastography Summary Shear Wave Elastography Summary

Unique to SuperSonic Imagine, due to need for advanced capabilities (SonicTouch, Ultrafast Imaging), and intellectual property protection.

Rich / complex mapping of hard lesions, with heterogeneous

elasticity in the lesion periphery and/or center.

23

Page 24: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Shear Wave Elastography ApplicationsShear Wave Elastography Applications

SWE is fully-integrated feature of the Aixplorer premium Ultrasound scanner.

24

Organs currently targeted by SWE include:• Breast, Thyroid, and Liver.

Work-in-progress encompasses:• Prostate, Musculoskeletal, and 3D Breast applications.

R&D efforts focus on Cardiovascular and Ophthalmology applications.

Page 25: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential25

Multi-center Breast Elastography TrialAssessment Of The Clinical Benefits Of SuperSonic

Shear Wave Elastography In The Ultrasonic Evaluation

Of Breast Lesions Dates: Q2 2008 to Q2 2010

Sites: 11 centers in Europe & 6 centers in USA Primary aim: Assess the benefit of Shear Wave Elastography for the characterization of breast lesions. Secondary aim: Assess the benefit of Shear Wave

Elastography for the visualisation of breast lesions.

Clinical trial and data analysis currently under way.

Preliminary results very promising. Improved sensitivity and specificity of breast ultrasound BIRADS diagnosis with SWE + ECHO versus ECHO only.

Page 26: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

Clinical Evaluation of SWE for Liver Fibrosis Staging

26

SWE: Fibroscan:

Bavu et al, “Non-invasive in-vivo Liver Fibrosis staging using Supersonic Shear Imaging: a Clinical Study”, Gastroenterology, 2010 (in press).

Page 27: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential

CONCLUDING REMARKSCONCLUDING REMARKS

27

Page 28: The information contained in this presentation is proprietary and confidential Βασικές αρχές της Ελαστογραφίας. Εξέλιξη της τεχνολογίας

The information contained in this presentation is proprietary and confidential28