Inverse finite element characterization of soft tissues.

In this work a tissue aspiration method for the in vivo determination of biological soft tissue material parameters is presented. An explicit axisymmetric finite element simulation of the aspiration experiment is used together with a Levenberg-Marquardt algorithm to estimate the material model parameters in an inverse parameter determination process. An optimal fit of the simulated experiment and the real experiment is sought with the parameter estimation algorithm. Soft biological tissue is modelled as a viscoelastic, non-linear, nearly incompressible, isotropic continuum. Viscoelasticity is accounted for by a quasi-linear formulation. The aspiration method is validated experimentally with a synthetic material. In vivo (intra-operatively during surgical interventions) and ex vivo experiments were performed on human uteri.