title: Fenestrations of the intracranial vertebrobasilar system diagnosed by MR angiography.
abstract: BACKGROUND
  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.
  
  
  CONCLUSIONS
  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.
authors: Department of Diagnostic Radiology, Saitama Medical University International Medical Center, 1397-1 Yamane, Hidaka, Saitama, Japan. auchino@saitama-med.ac.jp
authors: Akira
authors: A
authors: Uchino
authors: Naoko
authors: N
authors: Saito
authors: Yoshitaka
authors: Y
authors: Okada
authors: Eito
authors: E
authors: Kozawa
authors: Naoko
authors: N
authors: Nishi
authors: Waka
authors: W
authors: Mizukoshi
authors: Kaiji
authors: K
authors: Inoue
authors: Reiko
authors: R
authors: Nakajima
authors: Masahiro
authors: M
authors: Takahashi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001488:Basilar Artery / Q000002:abnormalities*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D002532:Intracranial Aneurysm / Q000175:diagnosis*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies; D014711:Vertebral Artery / Q000002:abnormalities*