Changes in Cerebral Aneurysm Hemodynamics After Virtual Endarterectomy

Abstract

Cerebral aneurysm hemodynamics depends on flow conditions at and geometry of parent vessels. Wall shear stress distributions and extreme values are widely accepted to be responsible for aneurysm initiation, growth and rupture. Those aneurysms may coexist with a proximal artery stenosis in a small number of patients. In those cases, that poses a challenge for interventional neuroradiologists and neurosurgeons to make the best treatment decision. For low and mild stenoses, flow alterations in the aneurysm sacs are limited when the aneurysm is located far downstream in the same circulation. However, for distal aneurysms close to the stenosis, intra-aneurysmal hemodynamics may be significantly affected by the stenosis. In this work we studied the changes in the wall shear stress distributions after virtual intervention in both ideal and patient-specific models. Three-dimensional rotational angiographic images were segmented using region growing and deformable model algorithms. Isosurface of the boundary was used to generate a volumetric mesh of tetrahedra in the domain using an advancing front technique. Numerical integration of the Navier-Stoke's equations was performed using a time dependent finite element formulation. Personalized inflow wave forms were imposed at the inlets and hemodynamic forces were studied at the systolic peak. Wall shear stress differences between the results of the simulations performed before and after virtual intervention were computed for different stenosis grades and different aneurysm locations.