title: Cortical Cerebral Blood Flow, Oxygen Extraction Fraction, and Metabolic Rate in Patients with Middle Cerebral Artery Stenosis or Acute Stroke.
abstract: OBJECTIVE
  With the advances of magnetic resonance technology, the CBF, oxygen extraction fraction, and cerebral metabolic rate of oxygen can be measured in MRI. Our aim was to measure the CBF, oxygen extraction fraction, and cerebral metabolic rate of oxygen use in patients with different severities of middle cerebral artery stenosis or acute stroke by using the arterial spin-labeling and susceptibility-weighted imaging techniques.
  
  
  METHODS
  Fifty-seven patients with MCA stenosis or acute stroke were recruited and classified into 4 groups: mild MCA stenosis (group 1), severe MCA stenosis (group 2), occluded MCA (group 3), and acute stroke (group 4). Arterial spin-labeling and SWI sequences were used to acquire CBF, oxygen extraction fraction, and cerebral metabolic rate of oxygen.
  
  
  RESULTS
  The oxygen extraction fraction in hemispheres with mild MCA stenosis (group 1) was remarkably higher than that in the contralateral hemisphere. In addition, hemispheres with severe MCA stenosis (group 2) had significantly lower CBF and a significantly higher oxygen extraction fraction than the contralateral hemisphere. Hemispheres with occluded MCA (group 3) or acute stroke (group 4) had a significantly lower CBF and cerebral metabolic rate of oxygen and a significantly higher oxygen extraction fraction than the contralateral hemisphere.
  
  
  CONCLUSIONS
  The oxygen extraction fraction gradually increased in groups 1-3. When this offset a decrease in CBF, the cerebral metabolic rate of oxygen remained at a normal level. An occluded MCA led to reduction in both the CBF and cerebral metabolic rate of oxygen. Moreover, the oxygen extraction fraction and cerebral metabolic rate of oxygen significantly increased and decreased, respectively, in the occluded MCA region during acute stroke.
authors.affiliation: From the Department of Medical Imaging (Z.L.), First Hospital of Nanchang City, The Third Affiliated Hospital of Nanchang University, Nanchang City, China wuxiaoshui@126.com.
authors.forename: Z
authors.identifier: http://orcid.org/0000-0002-8848-4905
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Preventive Medicine (Y.L.), Heze Medical College, HeZe, Shandong, China.
authors.forename: Y
authors.identifier: http://orcid.org/0000-0001-8050-2446
authors.initials: Y
authors.lastname: Li
mesh_terms: D000368:Aged; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003251:Constriction, Pathologic / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000378:metabolism / Q000473:pathology*; D010100:Oxygen / Q000378:metabolism*; D013113:Spin Labels; D020521:Stroke / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000473:pathology
chemical_list: D013113:Spin Labels; D010100:Oxygen