Introduction Theory Methods Experiments Results Application Summary Dr. Heiko Maaß Institut für...
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Introduction Theory Methods Experiments Results Application Summary Dr. Heiko Maaß Institut für Angewandte Informatik Noninvasive Measurement of Elastic Properties of Living Tissue Forschungszentrum Karlsruhe Forschungszentrum Karlsruhe Technik und Umwelt Technik und Umwelt
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Transcript of Introduction Theory Methods Experiments Results Application Summary Dr. Heiko Maaß Institut für...
Introduction
Theory
Methods
Experiments
Results
Application
Summary
Dr. Heiko Maaß Institut für Angewandte Informatik
Noninvasive Measurementof Elastic Properties
of Living Tissue
Forschungszentrum KarlsruheForschungszentrum KarlsruheTechnik und UmweltTechnik und Umwelt
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
Introduction
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
Introduction
Theory
Methods
Experiments
Results
Application
Summary
• Elastography
• Sonoelastic Imaging
• Strain Imaging
• Magnetic Resonance Elastography
State of the art
10-1000 Hzvibration
deformation
measurement using Ultrasound or MR-tomography
Introduction
Introduction
Theory
Methods
Experiments
Results
Application
Summary
Theory
0U)cnn( kik2
mjijkm sound CChristoffel-equation:
restricted to soft tissue (no bone or cartilage)
Phenomenological model
)material,v,c,(f loadsound
general approach
Introduction
Theory
Methods
Experiments
Results
Application
Summary
• incompressible• incompressible
• non-linear• non-linear
• anisotrop• anisotrop
• viscous• viscous
• temperature dependent• temperature dependent
• inhomogeneous
• plastic
Theory
• dependent on metabolism, innervation and perfusion
strain
stress
tensioncompression
liver1mm
Mechanical properties of biological tissue
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 tissue bone, cartilage gases
1000 2000 30000 4000 m/s
05
10152025
0 5 10 15 20
0
1
2
3
4
pene
trat
ion
dept
h in
cm
reso
luti
on in
mm
sound frequency in MHz
xe 0
~ fa
b
c
Introduction
Theory
Methods
Experiments
Results
Application
Summary
Methods
t
I
t
US
s
Tomography
t
s
Non-invasive testing principle
Introduction
Theory
Methods
Experiments
Results
Application
Summary
Experiments
F
US
Pos
FC = 1540 m/s
Testing devices
Introduction
Theory
Methods
Experiments
Results
Application
Summary
0
0,02
0,04
0,06
0,08
0,1
0 0,2 0,4 0,6
1
23
Results
compressive strain d
com
pres
sive
str
ess
in M
Pa
compressive strain d
com
pres
sive
str
ess
in M
Pa
Evaluation of the experimental series
regression analysis
33
2213 ddd aaa
)1( 2212 dddP PPE
dUE 1
2: parametric regression
3: general regression
1: origin tangential gradient
correlation analysis
Fat Liver
Spleen
MuscleKidney
linear0
0,02
0,04
0,06
0,08
0,1
0 0,2 0,4 0,6
Introduction
Theory
Methods
Experiments
Results
Application
Summary
origin gradient in MPa (compression)
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8
Results
sound speed in m/s
fat (soft)
fat (harder)liver
spleen
heart musclekidney
fat
liver
spleen
kidney
1400 1420 1440 1460 1480 1500 1520 1540 1560 1580 1600
post mortem
post mortem
intra vitamintra vitam
Ranges of sound speed and origin gradient
Introduction
Theory
Methods
Experiments
Results
Application
Summary
Applicationst
ress
strain t
0,5 1,00
tension
compression
-0,5-1,0
F(s)
Simulation of soft biological tissue
)aaa1(E 3t4
2t3t2t
Introduction
Theory
Methods
Experiments
Results
Application
SummarySummary
• 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
Introduction
Theory
Methods
Experiments
Results
Application
Summary
Thank you for paying attention
