Prediction of Atherosclerotic Changes in Cavernous Carotid Aneurysms Based on Computational Fluid Dynamics Analysis: a Proof-of-concept Study

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. 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 ( $$\xi$$ ) and segmented the surface exposed to blood residence time over 1 s ( $${S}_{\xi >1}$$ ). We measured the decrease in volume after flow diversion using the original time-of-flight MR angiography data. Calcifications were observed in the region with $${S}_{\xi >1}$$ . In addition, the ratio of $${S}_{\xi >1}$$ 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. 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.