
Second most prevalent cancer
worldwide 3

Fifth most common cause of cancer
related death 4

Early diagnosis is a huge factor in survival
Figure 1: Taken from Mehrabian, 2008. 1

Self Examination (Manual Palpation)

Mammography

Magnetic Resonance Imaging

Ultrasound

Biopsy

Images taken pre and post-compression

Stress-strain relationships in tissues are
analyzed

Reconstruction technique used to
determine elastic parameters of tissues

Tumours in breast tend to be abnormally
stiff compared to surrounding tissue

For each tissue type, only a single elastic
parameter

Young’s Modulus: E = σ/ε

Only valid for low strains

Significant errors associated with
technique

Generally more than one hyperelastic
parameter per tissue

Defined by strain energy functions

Valid for large strain values

Calculations more complicated
Figure 2: Taken from http://www.smpp.northwestern.edu/. . . 2

Reconstructing hyperelastic parameters
from data is an inverse problem

Involves initial estimates and numerous
iterations

Computerized proof of concept

Boundary conditions and geometry defined
consistent with real breast anatomy

Finite Element calculations performed in
ABAQUS to generate displacement data

Iterative inversion algorithm runs to
convergence leading to hyperelastic
parameter reconstruction
Before deformation
After deformation
Main
preimage
Main
postimage
Calculate displacement
field using OF
Calculate
Deformation Gradient
Latest artificial
deformed image
Initial
HEPs
Updated
HEPs
Calculate Stress
tensor using
ABAQUS
No
Averaging & updating HE
parameters (1 to 3)
Figure 3: Taken from Amooshahi 5
Converge
Yes
End

Construction of phantom with PVA,
Biocide, and heat-cool cycles

Unaxial test for parameter measurement

Pre and Post Compression US images are
taken

Hyperelastic parameters reconstructed

Breast cancer has high prevalence and
mortality rate

Early detection is vital for treatment and
ultimately survival

Elastography shows great potential as a
diagnostic tool with high specificity

Hyperelastic models allow us to
reconstruct parameters for high strain
1.
2.
3.
4.
5.
H Mehrabian. Soft Tissue Hyperelastic Parameter Reconstruction. Masters thesis submitted to the
University of Western Ontario. Supervisor: Abbas Samani. (2008)
Mechanical Properties of Soft Tissue. In Sitting Biomechanics Laboratory. Retrieved May 30th, 2010
from:http://www.smpp.northwestern.edu/Makhsous/Mechanical%20Properties%20of%20Soft%2
0Tissue.shtml
World Health Organization International Agency for Research on Cancer (2008).
"World Cancer Report". Retrieved on May 30th, 2010.
World Health Organization (February 2006). "Fact sheet No. 297: Cancer". Retrieved
on May 30th, 2010.
M Amooshahi. (Nov. 17, 2009) Classification of Breast Tumours Using Hyperelastic Elastography
PowerPoint presentation presented at the University of Western Ontario.