title: Carotid-anterior cerebral artery anastomosis on MR angiography: a university hospital-based study.
abstract: BACKGROUND
  Rarely in the anterior circulation, an anastomosis of the carotid and anterior cerebral arteries occurs when an anomalous branch arises from the ophthalmic segment of the internal carotid artery and anastomoses with the A1-A2 junction of the anterior communicating artery. Right-side predominance is known. To our knowledge, the incidence of carotid-anterior cerebral artery anastomosis has not been reported, so we researched cases in our institution records to determine incidence and investigated characteristic features of the condition on magnetic resonance (MR) angiography.
  
  
  METHODS
  To isolate such cases, we retrospectively reviewed cranial MR angiographic images of 3,491 consecutive patients in our institution.
  
  
  RESULTS
  We found three cases with carotid-anterior cerebral artery anastomosis (two men, one woman), representing an incidence of 0.086%. The anastomosis was on the right in all three cases. A normal A1 segment of the anterior cerebral artery (ACA) was present in two cases but could not be identified in the remaining case on MR angiographic images that included source images. Two of the three patients demonstrated associated arterial variations in their carotid systems.
  
  
  CONCLUSIONS
  On MR angiography, we observed a 0.086% incidence of carotid-anterior cerebral artery anastomosis in our institution and reaffirmed the right-side predominance of this anomaly. We found a high frequency of other associated arterial variations in the carotid system.
authors.affiliation: Department of Diagnostic Radiology, Saitama Medical University International Medical Center, 1397-1 Yamane, Hidaka, Saitama, 350-1298, Japan. auchino@saitama-med.ac.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Uchino
authors.forename: Naoko
authors.initials: N
authors.lastname: Saito
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Okada
authors.forename: Kaiji
authors.initials: K
authors.lastname: Inoue
mesh_terms: D000328:Adult; D000368:Aged; D020771:Anterior Cerebral Artery / Q000002:abnormalities*; D002339:Carotid Arteries / Q000002:abnormalities*; D020785:Central Nervous System Vascular Malformations / Q000175:diagnosis*; D005260:Female; D006785:Hospitals, University; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D012189:Retrospective Studies