title: Time course of vascular reactivity using repeated phase-contrast MR angiography in patients with carotid artery stenosis.
abstract: OBJECTIVE
  Cerebral vascular reactivity assessment is typically performed with 2 perfusion measurements before and after a vasodilatory challenge. The aim of this study was to assess the time course of the vasodilatory effect in the brain-feeding arteries after a challenge with acetazolamide in patients with a stenosis of the internal carotid artery (ICA).
  
  
  METHODS
  Twenty-one patients with a symptomatic ICA stenosis and 18 healthy control subjects underwent 2-dimensional phase-contrast MR angiography to repeatedly measure the blood flow (mL/min) in both ICAs at baseline and in 5-minute intervals for 30 minutes after intravenous administration of acetazolamide.
  
  
  RESULTS
  At baseline, the blood flow was significantly lower in the stenosed ICAs of patients (155 ± 17 mL/min) than in the contralateral ICAs (237 ± 21 mL/min, P<0.05) and the ICAs of healthy control subjects (249 ± 15 mL/min, P<0.05) and remained lower throughout the time course. The maximum vasodilatory effect in the stenosed ICAs was observed after 15.3 ± 0.9 minutes, which was significantly later than in the contralateral ICAs (within 12.9 ± 0.7 minutes, P<0.05) and healthy ICAs (within 12.8 ± 0.8 minutes, P<0.05).
  
  
  CONCLUSIONS
  The onset of the maximum vasodilatory effect after administration of acetazolamide is delayed in patients with a symptomatic ICA stenosis.
authors: Department of Radiology, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, the Netherlands. n.s.hartkamp@umcutrecht.nl
authors: Nolan S
authors: NS
authors: Hartkamp
authors: Jeroen
authors: J
authors: Hendrikse
authors: H Bart
authors: HB
authors: van der Worp
authors: Gert J
authors: GJ
authors: de Borst
authors: Reinoud P H
authors: RP
authors: Bokkers
mesh_terms: D000086:Acetazolamide; D000368:Aged; D002343:Carotid Artery, Internal / Q000473:pathology*; D016893:Carotid Stenosis / Q000473:pathology*; D003097:Collateral Circulation / Q000502:physiology; D004232:Diuretics; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow / Q000502:physiology; D013997:Time Factors; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
chemical_list: D004232:Diuretics; D000086:Acetazolamide