Fenestrations of the intracranial vertebrobasilar system diagnosed by MR angiography

Abstract

Introduction: Fenestrations of cerebral arteries are most common in the vertebrobasilar (VB) system, and magnetic resonance (MR) angiographic studies of these variations are sparse.

Methods: We retrospectively reviewed MR angiographic images of 3,327 patients; images were obtained using two 1.5-T imagers and picked up fenestrations of the intracranial vertebral artery (VA), VB junction, and basilar artery (BA) for evaluation.

Results: In 92 patients, we found 93 fenestrations (2.80%), which included 18 of the intracranial VA (0.54% prevalence), 6 of the VB junction (0.18%), and 69 of the BA (2.07%). Most VA fenestrations were large, and the posterior inferior cerebellar artery arose from the fenestrated segment in 10 patients (56%). Fenestrations of the VB junction were small and triangular. Sixty-five (94%) of the 69 BA fenestrations were located at the proximal segment and had small slit-like configurations. The anterior inferior cerebellar artery arose from the fenestrated segment in 27 patients (37%). We found 18 cerebral aneurysms in 16 (17%) of the 92 patients with fenestration but detected only one aneurysm at the fenestration.

Conclusion: The overall prevalence of fenestrations of the intracranial VB system was 2.77%. We found associated cerebral aneurysms relatively frequently but rarely at the fenestration.