title: Relationship between circle of Willis morphology on 3D time-of-flight MR angiograms and transient ischemia during vascular clamping of the internal carotid artery during carotid endarterectomy.
abstract: OBJECTIVE
  A potential source of complication at carotid endarterectomy (CEA) is cerebral ischemia caused by hypoperfusion during clamping of the carotid artery. Configuration of primary collateral pathways may be a major risk factor for development of transient cerebral ischemia during clamping. We investigated whether circle of Willis morphology on 3D time-of-flight (TOF) MR angiograms can reliably predict transient ischemia during vascular clamping of the internal carotid artery (ICA) in patients undergoing CEA.
  
  
  METHODS
  Three-dimensional TOF MR angiography and CEA were performed in 117 patients. Patients had unilateral stenosis (n = 86), unilateral stenosis with contralateral occlusion (n = 21), or bilateral severe stenosis (n = 10) of the ICA. Circle of Willis morphology on preoperative 3D TOF MR angiograms was analyzed and correlated with intraoperative history of ischemia during vascular clamping of the ICA.
  
  
  RESULTS
  Patients with unilateral stenosis or bilateral severe stenosis experienced transient ischemia during clamping of ICA at a low rate (11 [11%] of 96). In these groups, we found no specific circle of Willis patterns associated with development of intraoperative ischemia. However, patients with contralateral ICA occlusion experienced ischemia frequently during clamping of the ICA (12 [57%] of 21). In this group, incompleteness of the circle of Willis was significantly related to the risk of intraoperative ischemia (P =.005).
  
  
  CONCLUSIONS
  In patients without contralateral ICA occlusion, circle of Willis morphology on 3D TOF MR angiograms cannot predict the development of intraoperative ischemia. However, in patients with contralateral ICA occlusion, incompleteness of the posterior part of the circle of Willis is a significant risk factor for development of ischemia during vascular clamping of the ICA.
authors.affiliation: Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jeong Hyun
authors.initials: JH
authors.lastname: Lee
authors.forename: Choong Gon
authors.initials: CG
authors.lastname: Choi
authors.forename: Do Kyun
authors.initials: DK
authors.lastname: Kim
authors.forename: Geun Eun
authors.initials: GE
authors.lastname: Kim
authors.forename: Ho Kyu
authors.initials: HK
authors.lastname: Lee
authors.forename: Dae Chul
authors.initials: DC
authors.lastname: Suh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002343:Carotid Artery, Internal / Q000601:surgery; D016893:Carotid Stenosis / Q000601:surgery*; D002941:Circle of Willis / Q000473:pathology*; D003097:Collateral Circulation / Q000502:physiology; D004292:Dominance, Cerebral / Q000502:physiology; D016894:Endarterectomy, Carotid; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D007431:Intraoperative Complications / Q000175:diagnosis*; D002546:Ischemic Attack, Transient / Q000175:diagnosis*; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D013525:Surgical Instruments