Retrospective study on hemodynamic and morphological characteristics of posterior communicating artery aneurysms associated with fetal-type posterior cerebral artery and their correlation with rupture risk

The fetal-type posterior cerebral artery (fPCA) is a prevalent anatomical variant that may influence the hemodynamics and shape of posterior communicating artery aneurysms (PCoAAs). Nonetheless, its involvement in aneurysm rupture remains contentious. This study investigated hemodynamic and morphologic differences between PCoAA with and without fPCA and assessed the predictive value of inflow angle on the risk of rupture. We conducted a retrospective analysis of 80 PCoAA patients diagnosed via digital subtraction angiography, sourced from the database of the Second Hospital of Hebei Medical University (2013-2023). The aneurysms were categorized into 4 groups: unruptured without fPCA (UA group), ruptured without fPCA (RA group), unruptured with fPCA (UF group), and ruptured with fPCA (RF group). Computational fluid dynamics was employed to examine morphological parameters such as aspect ratio, long-neck ratio, wide-neck ratio, size ratio, inflow angle, and hemodynamic parameters such as wall shear stress (WSS), normalized WSS, low-shear area ratio (LSAR), and flow velocity. The Mann-Whitney U test was employed for statistical comparisons. There was a significant correlation between the inflow angle and rupture in both the groups with and without fPCA aneurysms (P < .001). The area under the receiver operating characteristic curve of the inflow angle was 0.942 (95% confidence interval: 0.892-0.993), and the optimal diagnostic threshold was 113.0°, with a sensitivity of 0.825 and a specificity of 0.975. From the hemodynamic perspective, aneurysms associated with fPCA showed a decrease in WSS (P < .001) and an increased LSAR (P < .001), which correlated with increased aneurysm size or irregular morphology. Compared with ruptured aneurysms without fPCA (RA group), ruptured fPCA aneurysms (RF group) exhibited higher WSS and lower LSAR (P < .05), consistent with the low-WSS rupture hypothesis. The presence of fPCA is associated with alterations in the hemodynamic stress distribution and an increased risk of PCoAA rupture. Inflow angle is a reliable morphologic predictor of aneurysm rupture, especially in aneurysms associated with fPCA. These findings contribute to risk stratification and clinical decision-making in PCoAA management.