title: Anatomic variations in the circle of Willis in patients with symptomatic carotid artery stenosis assessed with multidetector row CT angiography.
abstract: OBJECTIVE
  To assess the presence of anterior and posterior collateral pathways in the circle of Willis in patients with symptomatic carotid artery stenosis (SCAS) and to compare this to patients without carotid artery stenosis.
  
  
  METHODS
  Multislice CT angiography was performed in 91 patients and 91 control subjects. Using consensus reading, 2 observers evaluated the presence and diameter of the anterior communicating artery (AcomA), the A1 segments of the anterior cerebral arteries, the posterior communicating arteries (PcomA) and the P1 segments of the posterior cerebral arteries. Anterior or posterior pathways were assumed to be present if the diameter of continuous arterial segments was >1 mm; both A1 segments and AcomA anterior, and ipsilateral P1 segment and PcomA posterior. Comparison between patients and controls was performed using the chi(2) test.
  
  
  RESULTS
  In the patients we found significantly more hypoplastic (<1 mm) or invisible A1 segments (16 and 14 vs. 4 and 1, respectively, p < 0.01). The AcomA was invisible in 4 patients versus 1 control. An isolated compromised anterior pathway and a combined compromised anterior and posterior pathway occurred more frequently in the patients as compared to the controls; 9 versus 1% (p < 0.01) and 26 versus 4% (p < 0.01).
  
  
  CONCLUSIONS
  A compromised anterior collateral pathway, usually combined with a compromised posterior pathway, occurs more frequently in patients with SCAS as compared to controls, which suggests a relation between symptomatic carotid stenosis and an incomplete circle of Willis.
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands. annetwaaijer@planet.nl
authors.forename: A
authors.initials: A
authors.lastname: Waaijer
authors.forename: M S
authors.initials: MS
authors.lastname: van Leeuwen
authors.forename: H B
authors.initials: HB
authors.lastname: van der Worp
authors.forename: H J M
authors.initials: HJ
authors.lastname: Verhagen
authors.forename: W P T M
authors.initials: WP
authors.lastname: Mali
authors.forename: B K
authors.initials: BK
authors.lastname: Velthuis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016893:Carotid Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002533:Cerebral Angiography / Q000379:methods*; D002536:Cerebral Arteries / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation; D002941:Circle of Willis / Q000002:abnormalities* / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003097:Collateral Circulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*