Hemodynamic Features of Unruptured Cerebral Aneurysms before Rupture: A CFD Study

Objective: This study was designed to identify hemodynamic features of aneurysms prior to rupture in comparison with unruptured aneurysms. Materials and Methods: A retrospective data of four large unruptured aneurysms (pre-ruptured group) with sufficient films just pre-rupture was used. Matched with the same location and similar sizes, another four unruptured aneurysms (unruptured group) were in accordance with controls during the same time period and flow simulations were performed for hemodynamic analysis. Results: Compared with the unruptured group, the pre-ruptured group had significantly more irregular aneurysm shape, higher aspect ratio and lower aneurysm-averaged wall shear stress (p = 0.031, p = 0.039 and p = 0.042, respectively). Although pre-ruptured aneurysms had lower low wall shear stress (WSS) area and higher oscillatory shear index value, there was no significant difference between groups. Conclusions: Irregular shape, higher aspect ratio and low wall shear stress were relative with unruptured ICA aneurysms in predicting rupture. Those patients with these risk factors should be more prone to treatment even if with an unruptured aneurysm.