Improving the accuracy of computational fluid dynamics simulations of coiled cerebral aneurysms using finite element modeling.

Cerebral aneurysms are a serious clinical challenge, with ∼half resulting in death or disability. Treatment via endovascular coiling significantly reduces the chances of rupture, but the techniquehas failure rates of ∼20 %. This presents a pressing need to develop a method fordetermining optimal coildeploymentstrategies. Quantification of the hemodynamics of coiled aneurysms using computational fluid dynamics (CFD) has the potential to predict post-treatment outcomes, but representing the coil mass in CFD simulations remains a challenge. We use the Finite Element Method (FEM) for simulating patient-specific coil deployment for n = 4 ICA aneurysms for which 3D printed in vitro models were also generated, coiled, and scanned using ultra-high resolution synchrotron micro-CT. The physical and virtual coil geometries were voxelized onto a binary structured grid and porosity maps were generated for geometric comparison. The average binary accuracy score is 0.8623 and the average error in porosity map is 4.94 %. We then conduct patient-specific CFD simulations of the aneurysm hemodynamics using virtual coils geometries, micro-CT generated oil geometries, and using the porous medium method to represent the coil mass. Hemodynamic parameters including Neck Inflow Rate (Q neck ) and Wall Shear Stress (WSS) were calculated for each of the CFD simulations. The average relative error in Q neck and WSS from CFD using FEM geometry were 6.6 % and 21.8 % respectively, while the error from CFD using a porous media approximation resulted in errors of 55.1 % and 36.3 % respectively; demonstrating a marked improvement in the accuracy of CFD simulations using FEM generated coil geometries.

Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Dr. Michael Levitt declares the following financial interests which may be considered competing interests: Unrestricted educational grants: Medtronic Stryker Consulting: Medtronic Metis Innovative Aeaean advisers Stereotaxis Data safety monitoring board: Arsenal Equity interest: Hyperion Surgical Proprio Apertur Cerebrotech Synchron Fluid Biomed Stereotaxis Editorial board: Journal of NeuroInterventional Surgery Frontiers in Surgery These relationships have been reviewed and approved by the University of Washington in accordance with its conflict of interest policies.

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