title: Relationship between cerebral circulatory reserve and oxygen extraction fraction in patients with major cerebral artery occlusive disease: a positron emission tomography study.
abstract: OBJECTIVE
  The present study examined the relationship between circulatory and metabolic reserve in patients with hemodynamic impairment.
  
  
  METHODS
  Positron emission tomography was used to investigate 40 patients with major cerebral artery occlusive disease. The ratio of cerebral blood volume to cerebral blood flow (CBV/CBF) and vasoreactivity in response to hypercapnia (%CBF(hypercapnia)) and acetazolamide (ACZ) stress (%CBF(ACZ)) were measured to evaluate circulatory reserve. Oxygen extraction fraction (OEF) was measured to evaluate metabolic reserve. To detect relationships between circulation reserve and OEF, cerebral hemispheres were grouped into 5 or 6 stepwise groups based on reduction of circulation reserve.
  
  
  RESULTS
  OEF was significantly elevated in hemispheres with CBV/CBF > or =0.11 minutes and in hemispheres with %CBF(hypercapnia) <0%. OEF was significantly increased according to %CBF(ACZ) in hemispheres with %CBF(ACZ) <15% and plateaued at levels below -15%.
  
  
  CONCLUSIONS
  Metabolic reserve consumption began at CBV/CBF > or =0.11 minutes, CBF(hypercapnia) <0%, and CBF(ACZ) <15%.
authors.affiliation: Department of Strokology, Research Institute for Brain and Blood Vessels, Akita, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Yata
authors.forename: Akifumi
authors.initials: A
authors.lastname: Suzuki
authors.forename: Jun
authors.initials: J
authors.lastname: Hatazawa
authors.forename: Eku
authors.initials: E
authors.lastname: Shimosegawa
authors.forename: Ken
authors.initials: K
authors.lastname: Nagata
authors.forename: Mika
authors.initials: M
authors.lastname: Sato
authors.forename: Junta
authors.initials: J
authors.lastname: Moroi
mesh_terms: D000086:Acetazolamide / Q000494:pharmacology; D000328:Adult; D000368:Aged; D001921:Brain / Q000473:pathology; D002539:Cerebral Arterial Diseases / Q000175:diagnosis* / Q000473:pathology; D002560:Cerebrovascular Circulation; D002561:Cerebrovascular Disorders / Q000175:diagnosis / Q000473:pathology; D005260:Female; D006439:Hemodynamics; D006801:Humans; D006935:Hypercapnia; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption; D049268:Positron-Emission Tomography / Q000379:methods*
chemical_list: D000086:Acetazolamide; D010100:Oxygen