Intraoperative Image Correction Using a Biomechanical Model of the Human Head with Different Material Properties

Abstract

In order to improve the accuracy of image-guided neurosurgery, different biomechanical models have been developed to correct preoperative images w.r.t. intraoperative changes like brain shift or tumor resection. For the simulation of deformations of anatomical structures with different material properties, all existing biomechanical models use either appropriate boundary conditions or spatially varying material parameter values while assuming the same physical model for all anatomical structures. In this contribution, we propose a new approach which allows to couple different physical models. In our case, we simulate rigid, elastic, and fluid structures by using the appropriate physical description for each material, namely the Navier equation and the Stokes equation. To solve the resulting differential equations, we derive a linear matrix system for each region by applying the finite element method. Thereafter, the linear matrix systems are linked to one common linear matrix system. Our approach has been tested using synthetic as well as tomographic images. It turns out that the integrated treatment of rigid, elastic, and fluid structures significantly improves the predicted deformation results in comparison to a pure linear elastic model.