Predicting Aneurysm Occlusion After Flow Diversion: The Role of Aneurysm-Parent Artery Geometry

OBJECTIVE: Flow diverters (FD) have transformed complex aneurysm management, but incomplete aneurysm occlusion remains a significant concern, highlighting the need for practical predictors of successful treatment. While local flow dynamics are known to be critically influenced by parent artery-aneurysm (PA-aneurysm) geometry, their quantitative assessment in clinical settings is challenging. This study aimed to identify practical, readily measurable geometric predictors for complete aneurysm occlusion following FD treatment. METHODS: This retrospective study analyzed 119 intracranial aneurysms treated with FD between 2014 and 2023 at our center. Morphological and geometric parameters-including maximal diameter, PA-aneurysm inlet and outlet angles, and branch artery incorporation-were quantitatively measured from 3D rotational Digital Subtraction Angiography (DSA). Angiographic outcomes, categorized as complete occlusion or persistence, were assessed at a minimum of 18 months of follow-up without additional intervention. Independent predictors were identified using univariable and multivariable logistic regression. RESULTS: Aneurysm occlusion was achieved in 89 (74.8%) cases during a median angiographic follow-up of 19.8 months (interquartile range [IQR], 12.2-34.7). In multivariable analysis, a lower likelihood of aneurysm occlusion was significantly associated with a larger PA-aneurysm inlet angle (OR, 0.82 per 10° increase; 95% CI, 0.69-0.98; p = 0.045) and the presence of branch artery incorporation (OR, 0.25; 95% CI, 0.10-0.63; p = 0.004). While a larger neck diameter (OR, 0.94; 95% CI, 0.85-1.03) was also associated with a lower occlusion rate, this association did not reach statistical significance (p = 0.175). The developed multivariable model demonstrated acceptable predictive performance (AUC = 0.743; 95% CI, 0.632, 0.855). CONCLUSIONS: A smaller PA-aneurysm inlet angle and absence of branch artery incorporation are independent predictors of aneurysm occlusion after flow diversion. These readily measurable geometric parameters from diagnostic DSA may serve as practical and useful indicators for predicting FD treatment outcomes.