Prediction of atherosclerotic changes in cavernous carotid aneurysms based on computational fluid dynamics analysis: a proof-of-concept study

Purpose: Recent computational fluid dynamics (CFD) studies have demonstrated the concurrence of atherosclerotic changes in regions exposed to prolonged blood residence. In this proof-of-concept study, we investigated a small but homogeneous cohort of large, cavernous carotid aneurysms (CCAs) to establish the clinical feasibility of CFD analysis in treatment planning, based on the association between pathophysiology and hemodynamics. Methods: This study included 15 patients with individual large CCAs. We identified calcifications, which indicated atherosclerotic changes, using the masking data of digital subtraction angiography. We conducted a CFD simulation under patient-specific inlet flow rates measured using magnetic resonance (MR) velocimetry. In the post-CFD analysis, we calculated the blood residence time (ξ) and segmented the surface exposed to blood residence time over 1 s (S_ξ>1). We measured the decrease in volume after flow diversion using the original time-of-flight MR angiography data. Results: Calcifications were observed in the region with S_ξ>1. In addition, the ratio of S_ξ>1 to the surface of the aneurysmal domain exhibited a negative relationship with the rate of volume reduction at the 6- and 12-month follow-ups. Post-CFD visualization demonstrated that intra-aneurysmal swirling flow prolonged blood residence time under the condition of a small inlet flow rate, when compared to the aneurysmal volume. Conclusion: The results of this study suggest the usefulness of CFD analysis for the diagnosis of atherosclerotic changes in large CCAs that may affect the therapeutic response after flow diversion.