Hemodynamic and Morphological Factors Influencing Wall Integrity in Intracranial Aneurysms: A Comparative Study of Thin and Thick-Walled Aneurysms*

While often asymptomatic until rupture, Intracranial Aneurysms (IAs) can lead to subarachnoid hemorrhage, thus posing significant challenges. Clinical evaluation of IAs typically considers size and morphology, but hemodynamics-induced mechanisms responsible for the thinning or thickening of the wall, which can lead to wall weakening and failure, remain poorly understood. To elucidate such mechanisms, we analyzed surgical videos of clipped IAs to identify regions with different wall appearances and assigned them to group A: IAs with thin walls (n=24) or B: IAs with thick walls (n=12). Then, we compared shape and flow factors derived from CFD models reconstructed from 3D images. Results show statistically significant differences between groups A and B for wall shear stress (WSS) (p=0.06, OR=0.95), WSS gradient in neck zone (p=0.03, OR=0.98), flow impingement in dome zone (p=0.03, OR=1.05), vortex core line length (flow complexity) (p=0.03, OR=1.75), bottleneck factor (width/neck diameter) (p=0.02, OR=16.9), surface curvature (p=0.03, OR=1.7), and volume to ostium ratio (volume/neck area) (p=0.04, OR=3.02). In summary, IAs in group A were smaller, with wider necks, and were exposed to higher WSS and WSS gradients, leading to thinner walls. In contrast, IAs in group B were larger with smaller necks and had lower WSS and WSS gradients combined with flow impingements at the dome, leading to thicker walls.