title: Altered flow territories after extracranial-intracranial bypass surgery.
abstract: OBJECTIVE
  To prevent stroke after carotid sacrifice and to augment cerebral perfusion in patients with internal carotid artery (ICA) occlusion, high-flow extracranial-intracranial (EC-IC) bypass operations are performed. Although the function and efficacy of the bypass is monitored during surgery, the postoperative flow through the bypass is significantly lower than the flow in the contralateral ICA. Thus far, it is unknown whether decreased bypass flow is caused by a low tissue perfusion or by a relatively small flow territory.
  
  
  METHODS
  Seven patients, four with an atherosclerotic ICA occlusion and three with a giant aneurysm of the ICA, were investigated; each underwent a high-flow EC-IC bypass and permanent occlusion of the ICA. Cerebral blood flow was measured with arterial spin labeling perfusion magnetic resonance imaging. Separate flow territory mapping of the EC-IC bypass, contralateral ICA, and posterior circulation was performed with selective arterial spin labeling magnetic resonance imaging.
  
  
  RESULTS
  No significant difference was found in cerebral blood flow between the hemisphere ipsilateral to the EC-IC bypass (70.9 +/- 11.3 ml/min/100 g tissue), contralateral to the EC-IC bypass (71.9 +/- 14.3 ml/min/100 g tissue), and comparable findings in 50 healthy control participants (69.1 +/- 17.5 ml/min/100 g tissue). Paired analysis of the individual flow territories demonstrated a 15% volume reduction (P = 0.018) in flow territory of the EC-IC bypass compared with the contralateral side.
  
  
  CONCLUSIONS
  In the present study, we demonstrate the feasibility of selective arterial spin labeling magnetic resonance imaging for clinical follow-up of patients after high-flow EC/IC bypass surgery, providing both information on flow territories and the level of regional cerebral blood flow.
authors.affiliation: Department of Radiology, University Medical Center, Utrecht, The Netherlands. j.hendrikse@azu.nl
authors.forename: Jeroen
authors.initials: J
authors.lastname: Hendrikse
authors.forename: Albert
authors.initials: A
authors.lastname: van der Zwan
authors.forename: Lino M P
authors.initials: LM
authors.lastname: Ramos
authors.forename: Matthias J P
authors.initials: MJ
authors.lastname: van Osch
authors.forename: Xavier
authors.initials: X
authors.lastname: Golay
authors.forename: Cees A F
authors.initials: CA
authors.lastname: Tulleken
authors.forename: Jeroen
authors.initials: J
authors.lastname: van der Grond
mesh_terms: D000328:Adult; D000368:Aged; D001157:Arterial Occlusive Diseases / Q000503:physiopathology* / Q000628:therapy*; D002343:Carotid Artery, Internal / Q000503:physiopathology*; D002548:Cerebral Revascularization; D005260:Female; D007839:Functional Laterality; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow; D018709:Statistics, Nonparametric