Abstract: Objective To investigate the morphological and hemodynamic characteristics of intracranial mirror aneurysm and their effect on aneurysm rupture. 
Methods The data of 92 aneurysms in 46 patients with intracranial mirror aneurysms by digital subtraction angiography were analyzed retrospectively. Fifteen morphological parameters and 5 hemodynamic parameters of aneurysms were collected by computational fluid dynamics simulation.The difference of parameters between ruptured and unruptured aneurysms was compared, and the risk factors for ruptured aneurysms were determined by multivariate Logistic regression analysis. Receiver operating characteristic (ROC) curve was used to analyze each parameter to predict the area under ROC curve (AUC) and threshold of aneurysm rupture. 
Results The incidence of irregular shape and bleb formation in ruptured group were higher than that in unruptured group. Maximum diameter, height, width, maximum height(Hmax), bottle neck factor (BNF),aspect ratio (AR),size ratio (SR),height/width (H/W) and Hmax/width(Hmax/W) were higher than those in the unruptured group, and the average wall shear stress (WSS) and  normalized wall shear stress(NWSS) were lower than those in the unruptured group, with statistical significance (P＜0.05). There were no significant differences in the bifurcation, tumor neck width, diameter of parent vessel (DV), inflow angle, maximum wall shear stress (MWSS), average oscillatory shear index (OSI) and wall shear stress of parent artery (PTWSS) between two groups (P＞0.05). Multiple Logistic regression analysis showed that SR and bleb formation were risk factors for aneurysm rupture. ROC analysis results showed that the maximum diameter, height, Hmax and SR had high AUC values of 0.841, 0.820, 0.847 and 0.873, respectively. 
Conclusion Ruptured intracranial mirror aneurysms are more common in aneurysms with irregular shape and bleb formation, and have larger maximum diameter, height, width, Hmax, AR, SR, H/W, Hmax/W, and smaller WSS and NWSS. SR and bleb formation are independent risk factors for the rupture of intracranial mirror aneurysms. 

Key words: intracranial aneurysm, morphology, hemodynamics