title: Assessment of the contribution of the external carotid artery to brain perfusion in patients with internal carotid artery occlusion.
abstract: OBJECTIVE
  The purpose of this study was to prospectively investigate the contribution of the ipsilateral external carotid artery (ECA) to cerebral perfusion in patients with internal carotid artery occlusion.
  
  
  METHODS
  Institutional Review Board approval and informed consent were obtained. Thirty functionally independent patients (24 men, 6 women; mean age, 63 years) with an angiographically proven unilateral internal carotid artery occlusion and transient or minor disabling ischemic attacks ipsilateral to the side of the internal carotid artery occlusion were included. Grading of ECA collateral flow was performed with intraarterial digital subtraction angiography. The contribution of the ECA to regional cerebral blood flow was assessed with selective arterial spin labeling MRI. Differences in regional cerebral blood flow were analyzed with Student t test.
  
  
  RESULTS
  Twenty percent of the patients had ECA Grade 0 collateral flow (no filling of ophthalmic artery), 20% Grade 1 (filling of carotid siphon), and 60% Grade 2 (filling of anterior and/or middle cerebral artery) as demonstrated on digital subtraction angiography. Although in the Grade 1 group, the ECA supplied a smaller region of the brain compared with the Grade 2 group, the mean regional cerebral blood flow of the perfusion territory supplied by the ECA is similar (P=0.70) in the Grade 1 group (mean+/-SD 57+/-16 mL/min/100 g) and the Grade 2 group (60+/-12 mL/min/100g).
  
  
  CONCLUSIONS
  In patients with symptomatic internal carotid artery occlusion, focal brain regions may strongly depend on the contribution to cerebral perfusion of the ECA ipsilateral to the side of the internal carotid artery occlusion, even in patients with limited ECA collateral supply as demonstrated on digital subtraction angiography.
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands. p.j.vanlaar@umcutrecht.nl
authors.forename: Peter Jan
authors.initials: PJ
authors.lastname: van Laar
authors.forename: Jeroen
authors.initials: J
authors.lastname: van der Grond
authors.forename: Jochem P
authors.initials: JP
authors.lastname: Bremmer
authors.forename: Catharina J M
authors.initials: CJ
authors.lastname: Klijn
authors.forename: Jeroen
authors.initials: J
authors.lastname: Hendrikse
mesh_terms: D000368:Aged; D015901:Angiography, Digital Subtraction; D001157:Arterial Occlusive Diseases / Q000473:pathology*; D002340:Carotid Artery Diseases / Q000473:pathology*; D017536:Carotid Artery, Common / Q000473:pathology; D002342:Carotid Artery, External / Q000378:metabolism*; D002343:Carotid Artery, Internal / Q000473:pathology*; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012039:Regional Blood Flow; D013113:Spin Labels
chemical_list: D013113:Spin Labels