Hemodynamic factors are thought to play an important role in the initiation, growth, and rupture of cerebral aneurysms. This report describes a study of the associations between qualitative intra-aneurysmal hemodynamics and the rupture of cerebral aneurysms. Two hundred ten consecutive aneurysms were analyzed by using patient-specific CFD simulations under pulsatile flow conditions. The aneurysms were classified into categories by 2 blinded observers, depending on the complexity and stability of the flow pattern, size of the impingement region, and inflow concentration. A statistical analysis was then performed with respect to the history of previous rupture. Interobserver variability analysis was performed. Ruptured aneurysms were more likely to have complex flow patterns (83%, P < .001), stable flow patterns (75%, P = .0018), concentrated inflow (66%, P = <.0001), and small impingement regions (76%, P = .0006) compared with unruptured aneurysms. Interobserver variability analyses indicated that all the classifications performed were in very good agreement-that is, well within the 95% CI. A qualitative hemodynamic analysis of cerebral aneurysms by using image-based patient-specific geometries has shown that concentrated inflow jets, small impingement regions, complex flow patterns, and unstable flow patterns are correlated with a clinical history of prior aneurysm rupture. These qualitative measures provide a starting point for more sophisticated quantitative analysis aimed at assigning aneurysm risk of future rupture. These analyses highlight the potential for CFD to play an important role in the clinical determination of aneurysm risks.
