Middle cerebral arterial bifurcation aneurysms are associated with bifurcation angle and high tortuosity.

PURPOSE

To investigate the association of middle cerebral artery (MCA) bifurcation aneurysms with bifurcation morphology.

MATERIALS AND METHODS

205 patients were enrolled, including 61 patients with MCA bifurcation aneurysms and 144 non-aneurysmal subjects. Aneurysmal cases were divided into types C (aneurysm neck on extension of the parent artery centerline) and D (deviating neck). The radius of the parent artery M1 (R) and bilateral branches (R and R, respectively), smaller (φ) and larger (φ) lateral angles, bifurcation angle, and arterial tortuosity from parent vessel to bilateral branches (T and T, respectively) were analyzed. Logistic regression and receiver operator characteristic (ROC) curve analysis were performed to identify risk factors and predictive values for MCA aneurysm presence and types.

RESULTS

In aneurysmal MCA bifurcations, bifurcating angle, T, T and R were significantly larger (P<0.01), while φ was significantly smaller (P<0.001) than those in controls. The bifurcation angle, T and LogitP were better morphological parameters for predicting MCA aneurysm presence with the AUC of 0.795, 0.932 and 0.951, respectively. Significant (P<0.05) differences were observed in the bifurcation angle, φ, R, R and T between types C and D aneurysmal bifurcations. T was an independent factor in discriminating types C from D aneurysms with an AUC of 0.802.

CONCLUSIONS

Bifurcation angle and arterial tortuosity from the parent artery to the branch forming a smaller angle with the parent artery have a higher value in distinguishing MCA aneurysmal from non-aneurysmal ones, and the tortuosity from the parent artery to the contralateral branch is the best indicator for distinguishing types C from D aneurysmal bifurcations.