Blood Flow Analysis in Patient-Specific Cerebral Aneurysm Models with Realistic Configuration of Embolized Coils

In this study, we simulate the blood flow in 3D patient-specific model of the cerebral aneurysm embolized with coils. The patient-specific model of the cerebral aneurysm was constructed from clinical CT images. To represent a realistic configuration of embolized coils in the aneurysm, a virtual coil model was employed constructed by means of a coil insertion simulation based on the minimum energy principle. The packing density of embolized coils was approximately 30% which was higher than required values in clinical practice. A blood flow analysis was done by solving the N.S. and continuity equations numerically with the finite volume method under rigid wall assumption. The blood flow simulation revealed that the flow shear rate was locally increased near the coil surface imposing no-slip velocity, especially around the entrance of the aneurysm, and the increase/decrease of the overall shear rate in the aneurysm was determined by the coil configuration embolized in the aneurysm. The present simulation also revealed a difference of coil-insertion condition exhibited various gometric configuration of the embolized coil and it sometimes gave a unique case, in which the coils were mainly distributed in the deep region in the aneurysms, in other words the local packing density of the entrance region was low, resulting in the strong shear flow as compared before the coil embolization.