Morphological-Hemodynamic Characteristics of Intracranial Bifurcation Mirror Aneurysms

Many morphological and hemodynamic parameters have been proposed as promising aneurysm rupture status discriminators. Besides, a clear dichotomy between sidewall and bifurcation aneurysms was reported. In this study, we strove to evaluate the contribution of many reported morphological and hemodynamic parameters to retrospective rupture status determination in bifurcation aneurysms independent of patients' characteristics.

Computational fluid dynamics were performed on 16 patients with bifurcation mirror aneurysms (MANs). Each pair was divided into ruptured and unruptured groups. The morphological and hemodynamic factors were analyzed and compared. Receiver operating characteristics (ROC) analysis was performed, and the area under the ROC curve (AUC) was calculated for all parameters to quantify the predictability of each index and identify the optimal threshold.

Morphological (size, aspect ratio, size ratio, and height-width ratio) and hemodynamic (time-averaged mean wall shear stress [WSSmean], low WSS area [LSA]) parameters reached statistical significance (P < 0.05). Aneurysm irregular shape, oscillatory shear index (OSI), flow stability, inflow concentration, and impingement zone did not achieve significantly statistical differences (P = 0.508, P = 0.319, P = 0.523, P = 0.227, and P = 1.000, respectively). After ROC analysis, only aspect ratio and LSA had excellent AUC values (0.840 and 0.824, respectively). Other key parameters, including size, size ratio, height-width ratio, and WSSmean, had AUC values between 0.7 and 0.8 (0.730, 0.715, 0.703, 0.727, respectively).

Higher aspect ratio and LSA are good indicators for bifurcation aneurysm rupture. MANs with different rupture status might be a useful disease model in which many factors are balanced to investigate possible features linked to aneurysm rupture.