Hyperelastic Model Selection of Tissue Mimicking Phantom Undergoing Large Deformation and Finite Element Modeling for Elastic and Hyperelastic Material Properties

Pathologies in soft tissues are associated with changes in their elastic properties. Tumor tissues are usually stiffer than the fat tissues and other normal tissues and show the nonlinear behavior in large deformations. There have been a lot of researches about elastography (linear and nonlinear) as a new detecting technique based on mechanical behavior of tissue. In order to formulate the tissue’s nonlinear behavior, a strain energy function is required. For better estimation of nonlinear tissue parameters in elasticity imaging, non linear stress-strain curve of phantom is used. This work presents hyperelastic measurement results of tissue-mimicking phantom undergoing large deformation during uniaxial compression. For phantom samples, 8 hyperelastic models have been used. The results indicate that polynomial model with N=2 is the most accurate in terms of fitting experimental data. To compare the results between elastic and hyperelastic model, a 3-D finite element numerical model developed based on two different materials of elastic and hyperelastic material properties. The comparison confirm the approach of other recent studies about necessity of hyperelastic elastography and state that hyperelastic elastography should be used to formulate a technique for breast cancer diagnosis.