A Novel Composit Vascularized FEM Model for Liver Surgery Simulation and Guidance

In order to acquire comprehensive information from the limited visual feedback of liver surgery under endoscope, a liver model with high accuracy and low time consumption is indispensable. Many researchers has studied the biomechanical models of liver focusing on parenchyma elasticity and viscosity property in order to simulation the realtime deformation during the surgery, but only a few of them consider the vascular network. Some vascularized liver models contain ill-conditioned matrix issue that makes the choices of solver strictly limited. In the paper we propose a novel method to construct a real-time composite model in order to reduce this limitation. Instead of constructing the global stiffness matrix, we build FEM models for parenchyma and vessels separately and couple them with propagation of force and deformation. We apply a new mapping method to distribute the torque applied on the beam node to linear forces of the tetrahedron nodes. The simulation results show the feasibility of our method under certain precision.