Validation of quantitative linear and nonlinear compression elastography

Most efforts in elastography have focused on recovering the linear properties of tissues while ignoring their nonlinear behavior which becomes evident at large strains. This chapter briefly describes the solution of the inverse nonlinear elasticity problem, the ultrasound data acquisition, and the displacement estimation algorithm. It presents the reconstructions for the linear and nonlinear elastic parameters for the tissue‐phantom. The chapter discusses several algorithmic choices for the reconstruction algorithms. The inversion strategy uses a quasi‐Newton optimization algorithm coupled with a nonlinear finite element code. A phantom containing four spherical inclusions was manufactured using ultrasound phantom materials with nonlinear elastic properties. The displacement data used in generating the shear modulus and nonlinear parameter images was also used to generate axial strain images. The shear modulus reconstructions show that every data set contains a circular inclusion in the lower part of the image