1. Introduction Theory Methods Experiments Results Application Summary Dr. Heiko Maaß Institut für Angewandte Informatik Noninvasive Measurement of Elastic Properties of Living Tissue Forschungszentrum Karlsruhe Technik und Umwelt

2. Introduction Theory Methods Experiments Results Application Summary Quantitative evaluation of diagnostical results Quantification of tissue mechanics Monitoring of healing processes Mechanical properties in medicine Detection of hardenings or softenings (palpation) Introduction

3. Theory Methods Experiments Results Application Summary The 'Karlsruhe Endoscopic Trainer' simulation of elastic tissue product design biophysics accident research Application of mechanical tissue parameters Introduction

4. Theory Methods Experiments Results Application Summary Elastography Sonoelastic Imaging Strain Imaging Magnetic Resonance Elastography State of the art 10-1000 Hz vibration deformation measurement using Ultrasound or MR-tomography Introduction

5. Theory Methods Experiments Results Application Summary Theory Christoffel-equation: restricted to soft tissue (no bone or cartilage) Phenomenological model general approach

6. Introduction Theory Methods Experiments Results Application Summary incompressible non-linear anisotrop viscous temperature dependent inhomogeneous plastic Theory dependent on metabolism, innervation and perfusion liver 1mm Mechanical properties of biological tissue

7. Introduction Theory Methods Experiments Results Application Summary Theory skin fat liver heart muscle 10µm 1µm Histology

8. Introduction Theory Methods Experiments Results Application Summary Theory Acoustical properties of biological tissue velocity of sound damping a: penetration depth b: lateral resolution c: axial resolution soft tissuebone, cartilagegases 1000 2000 30000 4000 m/s penetration depth in cm resolution in mm sound frequency in MHz  ~ f a b c

9. Introduction Theory Methods Experiments Results Application Summary Theory purely longitudinal wave purely transversal wave propagation direction bulk wave Acoutsical methods of testing conductancereflection penetration continuousimpulses - damping - interferences - dispersion - propagation time measurements

10. Introduction Theory Methods Experiments Results Application Summary Methods tt ss Non-invasive testing principle

11. Introduction Theory Methods Experiments Results Application Summary Methods Simulation of the propagation of ultrasound waves

12. Introduction Theory Methods Experiments Results Application Summary Methods Screen shots of the ultrasound simulation

13. Introduction Theory Methods Experiments Results Application Summary Methods ultrasound device tomographical system graphic workstation position sensing system ultrasound head coupled with position sensor interaction Assembly used for the non-invasive measurement

14. Introduction Theory Methods Experiments Results Application Summary Experiments image overlay liver spatial orientation Performance of the sound speed measurement

15. Introduction Theory Methods Experiments Results Application Summary Experiments F US Pos F C = 1540 m/s   Testing devices

16. Introduction Theory Methods Experiments Results Application Summary 1 2 3 Results compressive strain  d compressive stress in MPa compressive strain  d compressive stress in MPa Evaluation of the experimental series regression analysis 2: parametric regression 3: general regression 1: origin tangential gradient correlation analysis

17. Introduction Theory Methods Experiments Results Application Summary Results Resulting curves compression test: heart muscle Compression test: kidney tension test: muscle, detailtension test: muscle (stationary)(mobile) strain compressive strain stress in N/mm²

18. Introduction Theory Methods Experiments Results Application Summary Results sound speed in m/s origin tangent E U in MPa liver tissue Correlation analysis results  2 = 1,2 E P  d (1 _ 3  d + 17  d 2 ) sound speed in m/s parameter E P in MPa  1 = E U  d origin tangent parametric regression series intra vitam series post mortem

19. Introduction Theory Methods Experiments Results Application Summary Results sound speed in m/s a 1 in MPa Correlation analysis results II sound speed in m/s general regression sound speed in m/s a 2 /a 1 a 3 /a 1 series intra vitam series post mortem liver tissue

20. Introduction Theory Methods Experiments Results Application Summary Results Graphical correlation analysis liver heart musclekidney spleenfat Abscissa: sound speed in m/s Ordinate: gradient of the origin tangent in MPa series intra vitam series post mortem

21. Introduction Theory Methods Experiments Results Application Summary origin gradient in MPa (compression) 00,10,20,30,40,50,60,70,8 Results sound speed in m/s fat (soft) fat (harder) liver spleen heart muscle kidney fat liver spleen kidney 14001420144014601480150015201540156015801600 post mortem intra vitam Ranges of sound speed and origin gradient

22. Introduction Theory Methods Experiments Results Application Summary Results Results of the measurements on human biceps Compression test on human biceps in vivo sound speed in m/s origin tangent in MPa tensed bicepsrelaxed biceps

23. Introduction Theory Methods Experiments Results Application Summary Application stress  strain  t 0,51,00 tension compression -0,5 -1,0 F(s) Simulation of soft biological tissue

24. Introduction Theory Methods Experiments Results Application Summary Development of new non-invasive methods of testing Usage of curve approximations in complex simulations Phenomenological model is not quantifiable Non-invasive differenciation of fat is possible Curve shapes are specific to the tissue kind Curves are independent on stress velocity Measurement of tissue parameters intra vitam Comparison to tisssue properties post mortem Simulation of the propagation of sound Development and employment of testing devices

25. Introduction Theory Methods Experiments Results Application Summary Thank you for paying attention