title: Can diffusion-weighted imaging-fluid-attenuated inversion recovery mismatch (positive diffusion-weighted imaging/negative fluid-attenuated inversion recovery) at 3 Tesla identify patients with stroke at <4.5 hours?
abstract: OBJECTIVE
  At 1.5 T, diffusion-weighted imaging-fluid-attenuated inversion recovery (DWI-FLAIR) mismatch helps identify strokes within 4.5 hours of onset. However, at 3T, studies have found divergent results. The goal of this study was to determine whether DWI-FLAIR mismatch at 3T would also be helpful for identifying patients within 4.5 hours of symptom onset.
  
  
  METHODS
  All patients presenting with an ischemic stroke in the middle cerebral artery territory and explored with 3T MRI within 12 hours between November 2007 and April 2012 were included in this retrospective study. Two readers analyzed the DWI and FLAIR images. Logistic regression was performed to determine independent predictors of FLAIR visibility. Also, the predictive values of a mismatch for identifying patients with stroke onset ≤4.5 hours were estimated.
  
  
  RESULTS
  The study included 194 patients. The only predictive factor of FLAIR visibility was delayed MRI acquisition. The DWI-FLAIR mismatch was able to identify patients within 4.5 hours of stroke onset with relatively low sensitivity (0.55; 95% confidence interval, 0.48-0.63), low specificity (0.60; 95% confidence interval, 0.42-0.77), high positive predictive value (0.88; 95% confidence interval, 0.82-0.94), and very low negative predictive value (0.19; 95% confidence interval, 0.11-0.28). In addition, 44.5% of patients had a positive FLAIR sequence within 4.5 hours.
  
  
  CONCLUSIONS
  This study improves our understanding of DWI-FLAIR mismatch as an imaging biomarker for wake-up management of patients with stroke. At 3T, the presence of a DWI-FLAIR mismatch was able to identify stroke onset of <4.5 hours. However, 44.5% of such stroke cases demonstrated FLAIR signal changes.
authors: Department of Neuroradiology, Hôpital Maison-Blanche, CHU de Reims, 45, rue Cognacq-Jay, 51092 Reims cedex, France.
authors: Samuel
authors: S
authors: Emeriau
authors: Isabelle
authors: I
authors: Serre
authors: Olivier
authors: O
authors: Toubas
authors: Francis
authors: F
authors: Pombourcq
authors: Catherine
authors: C
authors: Oppenheim
authors: Laurent
authors: L
authors: Pierot
mesh_terms: D000368:Aged; D002560:Cerebrovascular Circulation / Q000502:physiology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D019468:Disease Management; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000503:physiopathology*; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D020521:Stroke / Q000175:diagnosis* / Q000473:pathology* / Q000503:physiopathology; D013997:Time Factors
keywords: MRI; biomarker; brain imaging; ischemic stroke; penumbra stroke onset; thrombolysis acute stroke