title: Outcome of acute ischemic lesions evaluated by diffusion and perfusion MR imaging.
abstract: OBJECTIVE
  Diffusion and perfusion MR imaging have been reported to be valuable in the diagnosis of acute ischemia. Our purpose was to ascertain the value of these techniques in the prediction of ischemic injury and estimation of infarction size, as determined on follow-up examinations.
  
  
  METHODS
  We studied 18 patients with acute ischemic stroke who underwent echo-planar perfusion and diffusion imaging within 72 hours of symptom onset. Quantitative volume measurements of ischemic lesions were derived from relative mean transit time (rMTT) maps, relative cerebral blood volume (rCBV) maps, and/or apparent diffusion coefficient (ADC) maps. Follow-up examinations were performed to verify clinical suspicion of infarction and to calculate the true infarction size.
  
  
  RESULTS
  Twenty-five ischemic lesions were detected during the acute phase, and 14 of these were confirmed as infarcts on follow-up images. Both ADC and rMTT maps had a higher sensitivity (86%) than the rCBV map (79%), and the rCBV map had the highest specificity (91%) for detection of infarction as judged on follow-up images. The rMTT and ADC maps tended to overestimate infarction size (by 282% and 182%, respectively), whereas the rCBV map appeared to be more precise (117%). Significant differences were found between ADC and rMTT maps, and between rCBV and rMTT maps.
  
  
  CONCLUSIONS
  Our data indicate that all three techniques are sensitive in detecting early ischemic injury within 72 hours of symptom onset but tend to overestimate the true infarction size. The best methods for detecting ischemic injury and for estimating infarction size appear to be the ADC map and the rCBV map, respectively, and the diffusion abnormality may indicate early changes of both reversible and irreversible ischemia.
authors.affiliation: Department of Radiology, The University of Iowa Hospitals and Clinics, Iowa City 52242, USA.
authors.forename: T
authors.initials: T
authors.lastname: Ueda
authors.forename: W T
authors.initials: WT
authors.lastname: Yuh
authors.forename: J E
authors.initials: JE
authors.lastname: Maley
authors.forename: J P
authors.initials: JP
authors.lastname: Quets
authors.forename: P Y
authors.initials: PY
authors.lastname: Hahn
authors.forename: V A
authors.initials: VA
authors.lastname: Magnotta
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001810:Blood Volume / Q000502:physiology; D002545:Brain Ischemia / Q000175:diagnosis*; D002544:Cerebral Infarction / Q000175:diagnosis; D002560:Cerebrovascular Circulation / Q000502:physiology; D002561:Cerebrovascular Disorders / Q000175:diagnosis; D004058:Diffusion; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D014057:Tomography, X-Ray Computed