title: Identification of major ischemic change. Diffusion-weighted imaging versus computed tomography.
abstract: OBJECTIVE
  Thrombolytic therapy is not recommended in patients with CT changes of recent major infarction, which has been defined as reduced attenuation or cerebral edema involving >33% of the middle cerebral artery territory (European Cooperative Acute Stroke Study [ECASS] criteria). Diffusion-weighted imaging (DWI) is more sensitive than CT in detecting acute ischemia, and the combination of DWI, MR perfusion imaging, and MR angiography provides additional information from a single examination. We sought to determine whether DWI could identify the presence and extent of major ischemia as well as CT in hyperacute stroke patients.
  
  
  METHODS
  Seventeen suspected hemispheric stroke patients were studied with both CT and DWI within 6 hours of symptom onset. None received thrombolytic therapy. The scans were examined separately by 2 neuroradiologists in a blinded fashion for ischemic change and cerebral edema, graded as normal, <33%, or >33% of the MCA territory. Final diagnosis of stroke was determined with the use of standard clinical criteria and T2-weighted imaging at day 90.
  
  
  RESULTS
  Sixteen of 17 patients had a final diagnosis of stroke. Acute ischemic changes were seen in all 16 on DWI (100% sensitivity) and in 12 of 16 on CT (75% sensitivity). DWI identified all 6 patients with major ischemia on CT, with excellent agreement between the 2 imaging techniques (kappa=0.88). One patient eligible for thrombolysis on the ECASS CT criteria had major ischemia on DWI.
  
  
  CONCLUSIONS
  DWI is more sensitive than CT in the identification of acute ischemia and can visualize major ischemia more easily than CT.
authors.affiliation: Department of Neurology, Royal Melbourne Hospital, Australia.
authors.forename: P A
authors.initials: PA
authors.lastname: Barber
authors.forename: D G
authors.initials: DG
authors.lastname: Darby
authors.forename: P M
authors.initials: PM
authors.lastname: Desmond
authors.forename: R P
authors.initials: RP
authors.lastname: Gerraty
authors.forename: Q
authors.initials: Q
authors.lastname: Yang
authors.forename: T
authors.initials: T
authors.lastname: Li
authors.forename: D
authors.initials: D
authors.lastname: Jolley
authors.forename: G A
authors.initials: GA
authors.lastname: Donnan
authors.forename: B M
authors.initials: BM
authors.lastname: Tress
authors.forename: S M
authors.initials: SM
authors.lastname: Davis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001929:Brain Edema / Q000175:diagnosis; D000075202:Contraindications; D004058:Diffusion; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D015912:Thrombolytic Therapy; D014057:Tomography, X-Ray Computed