Development of a Virtual Coil Model for Blood Flow Simulation in Coil-Embolized Aneurysms

Hemodynamics is considered to be one of the indices to evaluate the effects of the treatment by coil embolization for cerebral aneurysms. For the sake of detailed analysis of hemodynamics in coil-embolized aneurysms, we develop a virtual coil model based on the mechanical theory that the coil deforms toward minimizing the elastic energy, and represent a realistic configuration of the embolized coils in the aneurysm by the insertion simulation. Then, the blood flow analysis is done by solving the N.S. and continuity equations numerically with the finite volume method using polyhedral mesh. The coil insertion simulation demonstrated that almost uniform distribution of the coil in the aneurysm was achieved at over 10% packing density of the coil. The blood flow analysis using the virtual coil model showed that the flow momentum inside the aneurysm was reduced to less than 10% by coil embolization with a packing density over 20%. In comparison to the simulation results using a porous media model for the embolized coil, there was no significant difference in the reduction ratio of the flow momentum in the aneurysm by coil embolization. However, local flow dynamics evaluated by the flow vorticity was different in the virtual coil model and the porous media model, in particular at the neck region of the aneurysm.