title: Azygous anterior cerebral artery and associated aneurysms: detection and identification using 3-dimensional time-of-flight magnetic resonance angiography.
abstract: OBJECTIVE
  The azygous anterior cerebral artery (Az) is a rarely observed anomaly of the anterior cerebral artery, and its associated aneurysm is even rarer. Our aim was to evaluate 3-dimensional time-of-flight magnetic resonance angiography (3-D-TOF MRA) in the diagnosis of Az and associated aneurysms.
  
  
  METHODS
  Three thousand five hundred seventy-two consecutive patients underwent 3-D-TOF MRA at 3.0 T. Postprocessing techniques, including volume rendering (VR) and single artery highlighting, were performed by a 3-D specialist. All MRA data and clinical information were recorded and stored in a database for further analysis.
  
  
  RESULTS
  Fourteen patients (.39%) were identified as having an Az. Among these cases, 3 males (21.43%) had an aneurysm located at the distal bifurcation of the Az, with a mean size of 9.43 ± 3.33 mm. In MRA, the common trunk of the Az was slightly larger in diameter than the A1 segment (2.62 ± .35 mm vs. 2.54 ± .35 mm; P = .008).
  
  
  CONCLUSIONS
  With the VR technique, 3-D-TOF MRA is feasible and valuable in detecting an Az and associated aneurysm. Our MRA-based study has proved that the Az is a rare anomaly but has a relatively high incidence of associated aneurysms.
authors.affiliation: Institute of Diagnostic and Interventional Radiology The Sixth Affiliated People's Hospital Shanghai Jiao Tong University No. 600, Yi Shan Road Shanghai, China.
authors.forename: Shi
authors.initials: S
authors.lastname: Wan-Yin
authors.forename: Li
authors.initials: L
authors.lastname: Ming-Hua
authors.forename: Gu
authors.initials: G
authors.lastname: Bin-Xian
authors.forename: Li
authors.initials: L
authors.lastname: Yong-Dong
authors.forename: Tan
authors.initials: T
authors.lastname: Hua-Qiao
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002536:Cerebral Arteries / Q000002:abnormalities* / Q000473:pathology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D002532:Intracranial Aneurysm / Q000209:etiology* / Q000473:pathology*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity