Fenestration of vertebrobasilar artery detected by MR angiography

Objective To describe the magnetic resonance angiography (MRA) features of vertebrobasilar artery fenestration and to evaluate the utility of MRA in the diagnosis of this anomaly.Methods Between April 2002 and April 2003,178 head and carotid three dimensional contrast enhanced MR angiographies were performed in our institution,most of the patients examined had or were suspected of having cerebrovascular disease.A 1.5-T scanner was used in all studies,after determination of the individual circulation time,CE MRA was performed during power injection of 20～30 ml of Gd-DTPA.Source images were processed using a workstation SGI-02,and image post-processing software was 3D Virtuoso,31VA.The reconstructed images were then processed into volume rending and maximal intensity projection (MIP) including region of interesting and thin slice multiplane reconstruction.These 178 angiograms were retrospectively reviewed.Results 10 fenestrations of vertebrobasilar artery were detected by CE MRA.Fenestration’s limb,length,anastomosis,and relationship between the anomaly and surrounding structures were clearly and surely displayed.The fenestrations were in the proximal portion of basilar artery trunk in 4 cases,3 fenestrations were present at vertebrobasilar junction,the other 3 fenestrations located in the vertebral artery,2 in left V4 and 1 in right V3.3 anomalies of basilar artery and all cases of vertebral artery showed true duplication type of fenestration,and the other 4 basilar fenestrations were minor,with their limb length less than 3 mm.In 4 patients there were additional cerebrovascular anomalies.Two of them were associated with cerebral true AVMs,the other 2 coexisted with persistent trigeminal artery,and a saccular aneurysm at the distal end of right vertebral artery was also found.Conclusion CE MRA can provide high quality angiograms of cerebral arterial system and is suitable for the detection of vertebrobasilar artery fenestration.