Prevalence, Geometry, and Hemodynamics of Small and Medium-Sized Intracranial Aneurysms With and Without Blebs in the Chinese Han Population.

Blebs are small bulges on the surface of intracranial aneurysms (IAs) that increase rupture risk. Among Chinese individuals, the prevalence, distribution, and clinical, geometric, and local hemodynamic characteristics of small- and medium-sized (<15 mm) blebbed IAs remain unclear. To investigate the prevalence, distribution, and associated clinical, geometric, and hemodynamic features of blebs in small- and medium-sized IAs among Chinese patients, and to identify predictors of aneurysm rupture and bleb formation. A retrospective observational study. CTA or DSA data from 214 patients with ruptured (RIAs) and unruptured IAs (UIAs) (<15 mm), with or without blebs, were analyzed. Three-dimensional reconstruction, geometric measurement, and computational fluid dynamics (CFD) analysis were conducted using Mimics and ANSYS Fluent. Hemodynamic parameters were assessed across the neck, body, and dome, and logistic regression was used to identify predictors of rupture and bleb formation. Aneurysms from 214 patients (93 men, 121 women; mean age 59.90 ± 11.76 years) were analyzed. Blebs were found in 107 aneurysms (56.7% of RIAs, 39.1% of UIAs). They were more frequent in ACoA, PCoA, and bifurcation aneurysms (all P < 0.05) and were associated with rupture. RIAs had larger blebs than UIAs (2.73 ± 1.28 mm vs 2.06 ± 1.07 mm, P = 0.009). Blebbed IAs exhibited larger size, more irregular shape, higher AR, SR, BN, HWR, and lower NWSS, TAWSS, OSI (all P < 0.05). SR was the strongest rupture predictor (AUC = 0.718, SR > 1.3144). Aneurysms at ACoA (OR = 8.812,CI:2.455-31.634), PCoA (OR = 6.376,CI:2.094-19.414), and high SR (OR = 2.738,CI:0.98-7.651) were significant rupture risk factors. PCoA (OR = 2.261,CI:0.759-6.739) and SR (OR = 4.683,CI:1.937-11.324) independently predicted bleb formation. Blebs are common in small- and medium-sized IAs, especially at the ACoA, PCoA, and bifurcations, and are associated with an increased risk of rupture. Larger blebs are more often seen in ruptured IAs. A high SR is a key predictor of both rupture and bleb formation. Further studies on bleb-related hemodynamics in the neck, body, and dome are warranted.