Relationship Between Geometry and Hemodynamics of MCA Aneurysms

A. J. GEERS; I. LARRABIDE; H. MORALES; A. F. FRANGI

Shangai

Simposio; 8th International Interdisciplinary Cerebrovascular Symposium.; 2011

Department of Neurosurgery, Shanghai Hospital

Purpose: Growth and rupture of cerebral aneurysms is related to intra-aneurysmal hemodynamics, which can be simulated using image-based vascular models and computational fluid dynamics (CFD) techniques. The main flow characteristics derived from these simulations have been validated and have shown to correlate with rupture status. The purpose of this study was to find relationships between simple-to-measure geometric descriptors of aneurysm shape and CFD-derived flow characteristics.Materials and Methods: Forty-three MCA bifurcation aneurysms imaged with 3DRA were drawn from the database of the European project @neurIST. Pulsatile blood flow simulations were created in ANSYS-CFX. Geometric descriptors of the aneurysm shape were automatically measured after delineation of the aneurysm neck. The main flow characteristics were classified using qualitative variables introduced by Cebral et al.Results: Aneurysms with simple vs. complex flow patterns had significantly lower nonsphericity (0.12 vs. 0.18, P = 0.006). Aneurysms with concentrated vs. diffuse inflow jets had significantly higher aspect ratios (1.43 vs. 0.84, P < 0.001). Aneurysms with small vs. large flow impingement sizes had significantly higher nonsphericity indices (0.19 vs. 0.12, P = 0.002) and significantly higher neck widths (5 mm vs. 4 mm, P = 0.02). No significant relationships with geometric variables were found for stable vs. unstable flow patterns.Conclusion: The strong relationship between the geometry and hemodynamics of aneurysms provides insight into the hemodynamic mechanisms underlying commonly measured geometric variables and might lead to new geometric variables that could serve as simple-to-measure estimators of flow characteristics.