Hemodynamic models of cerebral aneurysms for assessment of effect of vessel geometry on risk of rupture

Surgical decisions on treatment of cerebral aneurysms are based predominantly on aneurysm size. This study has assessed the influence of parent vessel geometry on intra-aneurysmal flow patterns and mass flow rate using computational fluid dynamics and finite element modeling of straight and curved vessels feeding saccular aneurysms of varying size and aspect ratio. Simulation results have shown that aneurysms of similar shape and size but with curved parent vessels can have more than 2 fold increase in flow rate, with markedly different flow velocity patterns and development of secondary flows. These are significant hemodynamic factors that can contribute to increased risk of aneurysm rupture, in addition to aneurysm size. The dependency of parent vessel geometry is a function of aneurysm aspect ratio and shows minimal dependency at an aspect ratio of 1.68. These findings could be used for improved quantification of risk of rupture of cerebral aneurysms detected from clinical imaging modalities and to aid surgical decision making.