title: Altered hemodynamics and regional cerebral blood flow in patients with hemodynamically significant stenoses.
abstract: OBJECTIVE
  Blood oxygen level-dependent (BOLD) contrast largely depends on changes in cerebral blood flow (CBF). Because cerebrovascular disease may result in altered CBF, we assessed the temporal dynamics and magnitude of the BOLD response in patients with major arterial stenoses.
  
  
  METHODS
  Seven patients with hemodynamically significant stenoses affecting the anterior circulation (primarily left internal carotid and middle cerebral arteries) were compared with 7 neurologically healthy subjects. Continuous arterial spin-labeled perfusion MRI was used to measure resting CBF globally and within various vascular distributions. The BOLD response was acquired during a visually guided bilateral handball squeeze task while motor performance was recorded by a pressure transducer.
  
  
  RESULTS
  Baseline CBF was reduced in bilateral middle cerebral artery and left anterior cerebral artery territories in patients. A prolonged BOLD hemodynamic response was observed in patients in bilateral primary motor cortices but not visual cortex. Patients also exhibited a larger early negative BOLD response, or "initial dip," in left primary motor cortex. There were no differences in motor performance between groups, suggesting behavioral differences were not primarily responsible for the characteristics of the BOLD response.
  
  
  CONCLUSIONS
  An initial deoxygenation followed by a delayed hyperemic BOLD response was observed in patients, although resting flow values were not within an ischemic range. A simple visuomotor BOLD activation paradigm can reflect alterations in the hemodynamic response in patients with hemodynamically significant stenoses.
authors.affiliation: Center for Functional Neuroimaging, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Anne C
authors.initials: AC
authors.lastname: Roc
authors.forename: Jiongjiong
authors.initials: J
authors.lastname: Wang
authors.forename: Beau M
authors.initials: BM
authors.lastname: Ances
authors.forename: David S
authors.initials: DS
authors.lastname: Liebeskind
authors.forename: Scott E
authors.initials: SE
authors.lastname: Kasner
authors.forename: John A
authors.initials: JA
authors.lastname: Detre
mesh_terms: D000328:Adult; D000792:Angiography; D001158:Arteries / Q000473:pathology; D001776:Blood Circulation Time; D001921:Brain / Q000473:pathology; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation; D003251:Constriction, Pathologic / Q000473:pathology; D005260:Female; D007839:Functional Laterality; D006439:Hemodynamics; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism; D011930:Reaction Time; D012039:Regional Blood Flow; D013997:Time Factors; D014793:Visual Cortex / Q000473:pathology
chemical_list: D010100:Oxygen