title: Severe occlusive carotid artery disease: hemodynamic assessment by MR perfusion imaging in symptomatic patients.
abstract: OBJECTIVE
  Cerebral hemodynamic status has been reported to influence the occurrence and outcome of acute stroke. The purpose of this study was to assess hemodynamic compromise in symptomatic patients with severe occlusive disease of the carotid artery by the use of echo-planar perfusion imaging.
  
  
  METHODS
  Spin-echo echo-planar perfusion imaging was performed in 11 patients (two had bilateral disease) with severe stenosis or occlusion of the carotid artery who had experienced either a recent transient ischemic attack or minor stroke. Relative cerebral blood volume (rCBV) maps and relative mean transit time (rMTT) maps were generated from the time-concentration curve. Findings on T2-weighted images, angiograms, rCBV maps, and rMTT maps were compared and assessed qualitatively and quantitatively.
  
  
  RESULTS
  Although the abnormalities on T2-weighted images were absent, minimal, and/or unrelated to the degree of stenosis or collateral circulation, rMTT maps showed much larger and more distinct perfusion abnormalities along the vascular distribution of the affected vessels in all 13 vascular territories of the 11 patients. Despite obvious abnormalities on rMTT maps, none of the patients had evidence of decreased rCBV in the affected brain tissue (increased in three, normal in eight). A statistically significant difference in rMTT values was found between the affected and unaffected brain tissue, whereas no significant difference was seen in rCBV values.
  
  
  CONCLUSIONS
  Echo-planar perfusion imaging is a noninvasive and rapid method for evaluating the hemodynamics in severe occlusive carotid artery disease and the compensatory vascular changes, and it may be useful in patient management.
authors.affiliation: Department of Radiology, University of Iowa College of Medicine, Iowa City 52242, USA.
authors.forename: M
authors.initials: M
authors.lastname: Maeda
authors.forename: W T
authors.initials: WT
authors.lastname: Yuh
authors.forename: T
authors.initials: T
authors.lastname: Ueda
authors.forename: J E
authors.initials: JE
authors.lastname: Maley
authors.forename: D L
authors.initials: DL
authors.lastname: Crosby
authors.forename: M W
authors.initials: MW
authors.lastname: Zhu
authors.forename: V A
authors.initials: VA
authors.lastname: Magnotta
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D001810:Blood Volume; D016893:Carotid Stenosis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation; D017352:Echo-Planar Imaging; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged