title: Effect of carotid endarterectomy on primary collateral blood flow in patients with severe carotid artery lesions.
abstract: OBJECTIVE
  In patients with severe obstruction of the internal carotid artery (ICA), it is recognized that the preoperative failure to visualize collaterals of the circle of Willis increases the risk of hemispheric ischemia before, during, and after carotid endarterectomy (CEA). The purpose of the present study was to assess the effect of CEA on the anatomy and function of the circle of Willis.
  
  
  METHODS
  Time-of-flight and phase-contrast MR angiography were used to study changes in vessel diameter and collateral flow of the circle of Willis in 48 patients with 70% to 99% ICA stenosis before and after CEA.
  
  
  RESULTS
  In patients with unilateral ICA stenosis, all preoperative vessel diameters on both sides of the circle of Willis were larger than in control subjects. All demonstrated a significant diameter decrease to reach normal values after CEA. Furthermore, preoperative collateral flow patterns normalized after CEA (P=0.03). In patients with stenosis and contralateral ICA occlusion, CEA resulted in a significant increase in the prevalence of collateral flow via the anterior communicating artery (33% to 83%, P<0.01) and a significant increase in diameter of both A1 segments (P<0.05) in patients in whom collateral flow developed after CEA.
  
  
  CONCLUSIONS
  CEA reduces the caliber of compensatory collateral channels to normal levels by MR angiography measurements in the presence of severe unilateral stenosis; when the opposite side is occluded and the stenosis is removed ipsilaterally, a greater amount of compensatory collateral circulation can be measured on both the occluded side and the fully opened side.
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands. j.hendrikse@azu.nl
authors.forename: Jeroen
authors.initials: J
authors.lastname: Hendrikse
authors.forename: Dirk R
authors.initials: DR
authors.lastname: Rutgers
authors.forename: Catharina J M
authors.initials: CJ
authors.lastname: Klijn
authors.forename: Bert C
authors.initials: BC
authors.lastname: Eikelboom
authors.forename: Jeroen
authors.initials: J
authors.lastname: van der Grond
mesh_terms: D000368:Aged; D015901:Angiography, Digital Subtraction; D001783:Blood Flow Velocity / Q000502:physiology; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000601:surgery; D016893:Carotid Stenosis / Q000175:diagnosis / Q000473:pathology / Q000601:surgery*; D002536:Cerebral Arteries / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002941:Circle of Willis / Q000502:physiology*; D003097:Collateral Circulation / Q000502:physiology*; D016894:Endarterectomy, Carotid; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D014463:Ultrasonography; D014654:Vascular Patency / Q000502:physiology*