Influence of Fetal-Type Posterior Cerebral Artery on Morphological Characteristics and Rupture Risk of Posterior...

Background/Objectives: The fetal-type posterior cerebral artery (fetal PCA) is an anatomical variant that alters hemodynamics and may influence posterior communicating artery (PCoA) aneurysm rupture risk. Aneurysm shape and size irregularity are key rupture predictors. This study investigates the impact of fetal PCA on PCoA aneurysm morphology and rupture risk using a radiomics-based approach. Methods: We retrospectively analyzed 87 patients with PCoA aneurysms (39 ruptured, 48 unruptured) treated at a tertiary center (January 2017-December 2022). Seventeen morphological parameters and 18 radiomic features were extracted per aneurysm. Patients were grouped by fetal PCA presence. Logistic regression and receiver operating characteristic (ROC) analyses identified rupture predictors. Results: Of 87 aneurysms, 38 had fetal PCA (24 ruptured, 14 unruptured), and 49 did not (15 ruptured, 34 unruptured). Fetal PCA was significantly associated with rupture (odds ratio [OR]: 3.28, p = 0.018). A higher non-sphericity index (NSI) correlated with rupture risk (OR: 3.35, p = 0.016). In non-fetal PCA aneurysms, size-related parameters such as height (6.83 ± 3.54 vs. 4.88 ± 2.57 mm, p = 0.034) and area (190.84 ± 167.08 vs. 107.94 ± 103.10 mm², p = 0.046) were key rupture predictors. In fetal PCA aneurysms, flow-related parameters like vessel angle (55.78 ± 31.39 vs. 38.51 ± 24.71, p = 0.035) were more influential. ROC analysis showed good discriminatory power, with an area under the curve: 0.726 for fetal PCA and 0.706 for NSI. Conclusions: Fetal PCA influences PCoA aneurysm rupture risk and morphology. NSI is a reliable rupture marker. Integrating morphological and anatomical data may improve rupture risk assessment and clinical decision-making.