title: PET OEF reactivity for hemodynamic compromise in occlusive vascular disease.
abstract: OBJECTIVE
  Hemodynamic compromise in symptomatic patients with occlusive vascular disease (OVD) identified by cerebrovascular reserve (CVR) and oxygen extraction fraction (OEF) is an independent predictor of high stroke risk. However, up to 60% of patients compromised by CVR have normal OEF indicating a high rate of discordance. CVR is measured with an acetazolamide challenge, and OEF reactivity (OEFR) to acetazolamide, ie, a hemodynamic challenge, may reveal hemodynamic compromise and less discordance with measurements of CVR.
  
  
  METHODS
  Nine symptomatic patients with OVD were studied by positron emission tomography before and 15 minutes after 15 mg/kg intravenous acetazolamide in the middle cerebral artery territories of each hemisphere.
  
  
  RESULTS
  A close correlation between hemispheric CVR and OEFR was observed. Two hemispheres from two different patients showed an increase in OEF to acetazolamide challenge despite a normal baseline OEF. The two hemispheres showing an increase in OEF in response to acetazolamide were also associated with the lowest CVR and severest white matter hyperintensities.
  
  
  CONCLUSIONS
  These observations suggest that positive OEFR may distinguish hemispheres in hemodynamic compromise despite normal OEF and show less discordance with CVR. However, these preliminary observations require confirmation in a larger study.
authors.affiliation: Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA. nemotoem@upmc.edu
authors.forename: Edwin M
authors.initials: EM
authors.lastname: Nemoto
authors.forename: Howard
authors.initials: H
authors.lastname: Yonas
authors.forename: Ronda R
authors.initials: RR
authors.lastname: Pindzola
authors.forename: Hiroto
authors.initials: H
authors.lastname: Kuwabara
authors.forename: Donald
authors.initials: D
authors.lastname: Sashin
authors.forename: Yuefang
authors.initials: Y
authors.lastname: Chang
authors.forename: Tudor
authors.initials: T
authors.lastname: Jovin
mesh_terms: D000086:Acetazolamide / Q000494:pharmacology; D000328:Adult; D000368:Aged; D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging / Q000378:metabolism; D002539:Cerebral Arterial Diseases / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery; D010100:Oxygen / Q000378:metabolism*; D049268:Positron-Emission Tomography; D020521:Stroke / Q000503:physiopathology; D014664:Vasodilation / Q000187:drug effects
chemical_list: D000086:Acetazolamide; D010100:Oxygen