Modelling anisotropic material property of cerebral aneurysms for fluid–structure interaction simulation

Cerebral aneurysms (CAs) are a kind of brain illnesses caused by the dilation of blood vessels with weakened walls and high health risks. The shape of CAs could be investigated by computed tomography angiography. Fluid–structure interaction (FSI) simulation is a useful tool to estimate the wall stress distribution and predict the rupture risk of a CA based on the shape. Accurate simulation is important to assist the treatment of CAs. Although the accuracy has been increased in recent years, the process still remains physically non-reasonable with most simulation studies relying on a uniform wall thickness and constant isotropic material property because the wall thickness and material directions are difficult to obtain in vivo. To address this issue, we present an anisotropic material property modelling scheme with a non-uniform wall-thickness distribution for patient-specific CAs in this article. The non-uniform wall-thickness distribution and material anisotropy are obtained through deforming the mesh of a healthy blood vessel onto an aneurysm model, where the mesh deformation simulates the formation of the aneurysm by stretching the mesh elements. With the addition of material anisotropy, the simulation results can be improved and become more physically meaningful.