title: Combining MRI with NIHSS thresholds to predict outcome in acute ischemic stroke: value for patient selection.
abstract: OBJECTIVE
  Selecting acute ischemic stroke patients for reperfusion therapy on the basis of a diffusion-perfusion mismatch has not been uniformly proved to predict a beneficial treatment response. In a prior study, we have shown that combining clinical with MR imaging thresholds can predict clinical outcome with high positive predictive value. In this study, we sought to validate this predictive model in a larger patient cohort and evaluate the effects of reperfusion therapy and stroke side.
  
  
  METHODS
  One hundred twenty-three consecutive patients with anterior circulation acute ischemic stroke underwent MR imaging within 6 hours of stroke onset. DWI and PWI volumes were measured. Lesion volume and NIHSS score thresholds were used in models predicting good 3-month clinical outcome (mRS 0-2). Patients were stratified by treatment and stroke side.
  
  
  RESULTS
  Receiver operating characteristic analysis demonstrated 95.6% and 100% specificity for DWI > 70 mL and NIHSS score > 20 to predict poor outcome, and 92.7% and 91.3% specificity for PWI (mean transit time) < 50 mL and NIHSS score < 8 to predict good outcome. Combining clinical and imaging thresholds led to an 88.8% (71/80) positive predictive value with a 65.0% (80/123) prognostic yield. One hundred percent specific thresholds for DWI (103 versus 31 mL) and NIHSS score (20 versus 17) to predict poor outcome were significantly higher in treated (intravenous and/or intra-arterial) versus untreated patients. Prognostic yield was lower in right- versus left-sided strokes for all thresholds (10.4%-20.7% versus 16.9%-40.0%). Patients with right-sided strokes had higher 100% specific DWI (103.1 versus 74.8 mL) thresholds for poor outcome, and the positive predictive value was lower.
  
  
  CONCLUSIONS
  Our predictive model is validated in a much larger patient cohort. Outcome may be predicted in up to two-thirds of patients, and thresholds are affected by stroke side and reperfusion therapy.
authors.affiliation: From the Departments of Radiology (P.W.S., B.P., W.A.C., J.A.H., T.L.-M., O.W., R.G.G., A.J.Y.) pschaefer@partners.org.
authors.forename: P W
authors.initials: PW
authors.lastname: Schaefer
authors.affiliation: From the Departments of Radiology (P.W.S., B.P., W.A.C., J.A.H., T.L.-M., O.W., R.G.G., A.J.Y.).
authors.forename: B
authors.initials: B
authors.lastname: Pulli
authors.affiliation: From the Departments of Radiology (P.W.S., B.P., W.A.C., J.A.H., T.L.-M., O.W., R.G.G., A.J.Y.).
authors.forename: W A
authors.initials: WA
authors.lastname: Copen
authors.affiliation: From the Departments of Radiology (P.W.S., B.P., W.A.C., J.A.H., T.L.-M., O.W., R.G.G., A.J.Y.).
authors.forename: J A
authors.initials: JA
authors.lastname: Hirsch
authors.affiliation: From the Departments of Radiology (P.W.S., B.P., W.A.C., J.A.H., T.L.-M., O.W., R.G.G., A.J.Y.).
authors.forename: T
authors.initials: T
authors.lastname: Leslie-Mazwi
authors.affiliation: Neurology (L.H.S.), Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: L H
authors.initials: LH
authors.lastname: Schwamm
authors.affiliation: From the Departments of Radiology (P.W.S., B.P., W.A.C., J.A.H., T.L.-M., O.W., R.G.G., A.J.Y.).
authors.forename: O
authors.initials: O
authors.lastname: Wu
authors.affiliation: From the Departments of Radiology (P.W.S., B.P., W.A.C., J.A.H., T.L.-M., O.W., R.G.G., A.J.Y.).
authors.forename: R G
authors.initials: RG
authors.lastname: González
authors.affiliation: From the Departments of Radiology (P.W.S., B.P., W.A.C., J.A.H., T.L.-M., O.W., R.G.G., A.J.Y.).
authors.forename: A J
authors.initials: AJ
authors.lastname: Yoo
mesh_terms: D000368:Aged; D001921:Brain / Q000473:pathology; D002545:Brain Ischemia / Q000473:pathology* / Q000628:therapy; D002544:Cerebral Infarction; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009316:National Institutes of Health (U.S.); D018579:Patient Selection; D011379:Prognosis; D012372:ROC Curve; D015424:Reperfusion; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D020521:Stroke / Q000473:pathology* / Q000628:therapy; D014481:United States