title: Visual perfusion-diffusion mismatch is equivalent to quantitative mismatch.
abstract: OBJECTIVE
  The concept of stroke MRI mismatch based on qualitative evaluation of diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) has been applied in clinical practice for several years. The benefit of MRI in providing pathological evidence of ischemia before thrombolytic treatment has been demonstrated. The purpose of this study is to determine the reliability of the qualitative method and compare it with quantitative mismatch measurement in thrombolytic-treated patients.
  
  
  METHODS
  Patients (n=70) were selected from the Lesion Evolution of Stroke and Ischemic On Neuroimaging (LESION) database if they: (1) were treated with intravenous recombinant tissue plasminogen activator; (2) had a pretreatment MRI with evaluable DWI and PWI; and (3) had acute ischemic lesion volume >10 mL on DWI as determined by core imaging laboratory measurements. Quantitative mismatch was defined as a difference of >50 mL between abnormal mean transit time and DWI volumes. Sample characteristics and postdischarge modified Rankin Scale for the positive mismatch patients were compared between the subgroups identified by qualitative versus quantitative methods.
  
  
  RESULTS
  Patient characteristics and thrombolytic outcomes (sex, age, National Institutes of Health Stroke Scale, mismatch volume, and modified Rankin Scale) did not differ for mismatch patients identified by qualitative versus quantitative methods. Qualitative mismatch selection among neurologists had a high sensitivity (0.82), specificity (0.80), accuracy (0.81), and positive predictive value (0.88) compared with quantitative measurements.
  
  
  CONCLUSIONS
  We observed that qualitative evaluation of mismatch identified the same thrombolytic-treated patients compared with retrospective quantitative mismatch measurements.
authors.affiliation: Section on Stroke Diagnostics and Therapeutics, 10 Center Drive, MSC 1063, Building 10, Room B1D733, Bethesda, MD 20892-1063, USA. lubym@ninds.nih.gov
authors.forename: Marie
authors.initials: M
authors.lastname: Luby
authors.forename: Katherine D
authors.initials: KD
authors.lastname: Ku
authors.forename: Lawrence L
authors.initials: LL
authors.lastname: Latour
authors.forename: José G
authors.initials: JG
authors.lastname: Merino
authors.forename: Amie W
authors.initials: AW
authors.lastname: Hsia
authors.forename: John K
authors.initials: JK
authors.lastname: Lynch
authors.forename: Steven
authors.initials: S
authors.lastname: Warach
mesh_terms: D000368:Aged; D002545:Brain Ischemia / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D001931:Brain Mapping / Q000379:methods; D002560:Cerebrovascular Circulation / Q000502:physiology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D020521:Stroke / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D015912:Thrombolytic Therapy / Q000379:methods*