A Model of Stress Relaxation for Brain Retraction Simulation

Abstract

Brain retraction is an important surgical technique that is used for lesion exposure in brain surgeries. However, in brain retraction, an excessive load may cause permanent damage to the brain. Therefore, the development of surgical simulators that can simulate the stress and force of brain reaction in advance of a real surgery is required.

In order to simulate brain retraction, a numerical calculation model of a viscoelastic body using the finite element method (FEM) was proposed. It is based on the generalized Maxwell model but considers the inertial term. The main advantage of including the inertial term is computational stability. The viscoelastic parameters were identified by the results of retraction experiments using whole porcine brains. Retraction experiments were performed with two retraction velocities, 1 mm/s and 10 mm/s. The parameters of the proposed model were identified by solving optimization problems using the retraction experimental results of the retraction velocity 10 mm/s. Retraction simulations (retraction velocity : 1 mm/s and 10 mm/s) were performed under the same conditions as in the experiments. The 3D simulation model was built from MRI data of a porcine brain. Comparing the simulation results and experimental data, it is confirmed that the viscoelastic model using the identified parameters simulated the brain retraction well.