Wall enhancement of intracranial unruptured aneurysm is associated with increased rupture risk and traditional risk factors.

OBJECTIVE: Aneurysm wall enhancement (AWE) on MRI has been considered an imaging marker to indicate active aneurysm inflammation, but no prospective studies have assessed the ability of AWE to predict rupture risk or growth. We aim to study the association of AWE with traditional risk factors and the estimated rupture risk.

METHODS: Seventy-seven patients (mean age, 58.4 ± 10.8 years; 57% female) with 88 asymptomatic intracranial saccular aneurysms underwent both 3-T high-resolution MRI and three-dimensional (3D) rotational digital subtraction angiography (DSA). Geometric and morphologic parameters were measured on DSA, and the degree of AWE on MRI was graded. One- and 5-year rupture risks of aneurysms were estimated using the UCAS and PHASES calculator. Parameters associated with AWE were analyzed using uni- and multivariate logistic regression.

RESULTS: Non-internal carotid artery location (OR 3.4, 95% CI 1.6-7.1) and aneurysm size (OR 1.9, 95% CI 1.3-2.7) were independently associated with AWE (p < 0.05). Aneurysms with AWE had significantly higher estimated rupture risk (1 and 5 year, 1.9% and 5.8%) than aneurysms without AWE (0.5% and 2.1%) (p < 0.001). Stronger and larger areas of AWE were correlated with the aneurysm size, size ratio and estimated rupture risk (R2 ≥ 0.30) (p < 0.01).

CONCLUSIONS: Prospective assessment of asymptomatic intracranial aneurysms with MRI suggests that AWE is associated with traditional risk factors and estimated short- and medium-term rupture risk.

KEY POINTS: • AWE independently associates with aneurysm location and size. • Aneurysms with AWE have higher rupture risk than aneurysms without AWE. • Stronger and larger areas of AWE correlated with the aneurysm size, size ratio and rupture risk.