Three-Dimensional Volumetric Assessment Enhances Detection of Growth in Unruptured Intracranial Aneurysms

Monitoring unruptured intracranial aneurysms (UIAs) is critical for guiding treatment, but conventional two-dimensional size-based monitoring may miss subtle growth and underestimate rupture risk. Aneurysm volume may offer a more sensitive alternative. This study evaluated the effectiveness of volumetric analysis in detecting significant growth compared to standard size-based assessment in routine clinical management. Patients undergoing UIA surveillance from January 2024 to January 2025 with baseline and follow-up angiographic imaging ≥ 4 months apart were included. Aneurysm size was obtained from clinical records. Volumetric growth was defined using a logistic mixed model-derived threshold; 2D growth was defined as increase in maximal diameter ≥ 1 mm. Logistic regression identified predictors of volumetric growth. Twenty-four out of 123 aneurysms (98 patients) demonstrated significant volumetric growth (≥ 50%), were more frequent in high-risk locations (58% vs 26%, p = 0.006), and had smaller baseline volume (median 14.6 vs 29.6 mm³, p = 0.008) with substantially elevated growth rates (median 35% vs 4% per year, p < 0.0001). Volumetric assessment detected all 2D growth cases (n 8) and identified 16 additional aneurysms that showed minimal 2D growth (median change 4% vs 38%). Logistic regression identified follow-up time (aOR 1.20 (1.03–1.42), p = 0.02) and high-risk location (aOR 6.96 (1.93–33.6), p = 0.006) as predictors of volumetric growth (AUC of 0.79). Volumetric analysis detects aneurysm growth more effectively than 2D assessments in small aneurysms. Growth was associated with longer follow-up and high-risk locations, highlighting the potential of volumetric assessment to improve UIA surveillance and guide decision-making.