title: The value of phase-contrast magnetic resonance angiography of the circle of Willis in predicting cerebral ischemia-hypoxia (shunt need) during carotid endarterectomy.
abstract: BACKGROUND
  Cerebral perfusion during carotid cross-clamping depends on collateral function of the circle of Willis. The aim of this study was to determine the value of 3D Phase-Contrast (3D PC) MR angiography in predicting pre-operatively the need of shunting.
  
  
  METHODS
  3D PC MR angiography were performed in 121 patients before carotid endarterectomy under locoregional anaesthesia. Based on the MR analysis, the risk of cerebral ischemia-hypoxia during clamping was classified as high, moderate and low. The analysis was then correlated with intraoperative neurological examination.
  
  
  RESULTS
  In patients with high risk of cerebral ischemia (n=9), immediate cerebral ischemia developed in all patients within one min of clamping (P<0.001). All nine underwent shunt placement. In six of the patients with moderate risk (n=46), cerebral ischemia occurred between 20 and 25 min after clamping; All occurred during intraoperative hypotension.
  
  
  CONCLUSIONS
  3D PC MR angiography can significantly determine the need of shunting in patients with important risk of immediate intraoperative cerebral ischemia. It also focuses on the intraoperative blood pressure stability in patients with moderate risk of ischemia.
authors.affiliation: Department of Thoracic and Vascular surgery, Avicenne Hospital, AP-HP, University Paris XIII, Bobigny, France. Patrick.BAGAN@hop.egp.ap-hop-paris.fr
authors.forename: P
authors.initials: P
authors.lastname: Bagan
authors.forename: J
authors.initials: J
authors.lastname: Azorin
authors.forename: J
authors.initials: J
authors.lastname: Salama
authors.forename: J-L
authors.initials: JL
authors.lastname: Dumas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001166:Arteriovenous Shunt, Surgical; D016893:Carotid Stenosis / Q000601:surgery; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002941:Circle of Willis / Q000473:pathology*; D003097:Collateral Circulation / Q000502:physiology; D003250:Constriction; D003287:Contrast Media; D016894:Endarterectomy, Carotid; D005260:Female; D006801:Humans; D020925:Hypoxia-Ischemia, Brain / Q000517:prevention & control*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007431:Intraoperative Complications / Q000517:prevention & control*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors
chemical_list: D003287:Contrast Media