Predicting Atherosclerosis in Unruptured MCA Aneurysm with Computational Fluid Dynamics (CFD) Study

Abstract Computational fluid dynamics (CFD) is being evaluated as a potential tool in diagnosing aneurysm hemodynamics. We have undertaken this study to evaluate the use of CFD as a tool to predict the atherosclerotic changes in unruptured middle cerebral artery (MCA) bifurcation aneurysm. In our study, we have compared the CFD images with intraoperative microscopic images of the MCA aneurysm. The purpose of our study was to find correlation between the CFD findings for the atherosclerotic changes in MCA bifurcation aneurysms. In aneurysms with atherosclerotic changes, there is risk of shower of emboli during the manipulation or placing of the clip because it can break the unstable local plaque resulting in distal arterial occlusion. To find the correlation between CFD studies and the atherosclerotic changes occurring in the MCA bifurcation aneurysm. A retrospective review of all intraoperative video recordings of patients with unruptured MCA bifurcation aneurysm from September 2014 to May 2017 at our hospital, Banbuntane Hotokukai Hospital, Fujita University, Nagoya, Aichi, Japan, was done. This is a single-center based study. Videos having atherosclerotic changes were selected. MCA bifurcation aneurysms with atherosclerotic changes were analyzed with CFD. We studied wall pressure, magnitude, and vectors of wall shear stress and streamline (flow pattern). The CFD findings were correlated with intraoperative findings. All the patients who were selected for this study had undergone open surgery. We found that there was decreased wall pressure in the areas of atherosclerotic changes. Low shear stress magnitude was seen in the atherosclerotic segment and there was divergent pattern of the shear stress vectors predicting the thick-walled segment with decreased flow velocity. Here, we have discussed four cases showing moderately decreased wall pressure in atherosclerotic segment and decreased wall shear stress magnitude in all these cases. Limitations of the study: This is a very small cohort study to establish any statistically significant correlation between the CFD findings and to predict atherosclerosis in MCA aneurysm. Hence, there is need of large multicentric cohort studies to establish the correlation and the statistical significance of the CFD findings in atherosclerosis.