title: [Imaging characteristics of basilar artery hypoplasia].
abstract: OBJECTIVE
  To determine the imaging characteristics of basilar artery hypoplasia (BAH).
  
  
  METHODS
  From October 2009 to August 2013, 10 193 magnetic resonance angiogram (MRA) and 31 716 magnetic resonance imaging (MRI) consecutive cases were retrospectively retrieved from our institutional Picture Archiving and Communication System (PACS) database. BAH was defined as a continuous diameter reduction all over artery and a basilar artery diameter ≤ 2 mm. The same cut-off value was applied for vertebral artery hypoplasia (VAH). We measured the diameters of basilar and vertebral arteries with PACS in all patients according to source imaging and IMP construction of MRA. The carotid arterial computed tomography angiogram (CTA) profiles were reviewed in 50 patients. The fetal-type posterior circle of Willis (FTP) was assessed. The diagnosis of acute cerebral infarction was based on clinical symptoms, signs and a high signal on diffusion-weighted imaging (DWI). Acute cerebral infarction was divided into anterior circulation stroke (ACS) and posterior circulation stroke (PCS).
  
  
  RESULTS
  A total of 210 BAH were identified among 10 193 consecutive patients. BAH was more common in females (56.7%) than males (43.3%) in the patient group. They had a fetal-type of posterior cerebral artery (FTP) (175 bilateral (83.3%), 35 unilateral (16.7%)). 99.5% patients had V4 VAH and 56.0% (28/50) V1-V3 VAH. Among 210 BAH, there are 74 patients (mean age 64 years, average 25-91 years, 44 males) with a diagnosis of acute cerebral infarction (ACI). The males were predominant in ACI (59.5% in males vs 40.5% in females, P = 0.021). The frequency of BAH was detected in 74 (2.2%) among 3 294 ACI patients.
  
  
  CONCLUSIONS
  As a relatively rare vascular abnormality, BAH has always unilateral or bilateral FTP and V4 VAH.
authors.affiliation: Department of Radiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China. Email: guhuahh@126.com.
authors.forename: Hua
authors.initials: H
authors.lastname: Gu
authors.affiliation: Department of Radiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Qian
authors.affiliation: Department of Radiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China.
authors.forename: Shuangkun
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Radiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Min
authors.affiliation: Department of Radiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China.
authors.forename: Wanhong
authors.initials: W
authors.lastname: Lu
authors.affiliation: Department of Radiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China.
authors.forename: Wenli
authors.initials: W
authors.lastname: Hu
mesh_terms: D001488:Basilar Artery; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging; D008297:Male; D012189:Retrospective Studies; D020521:Stroke; D014057:Tomography, X-Ray Computed; D014711:Vertebral Artery