title: Fluid-Attenuated Inversion Recovery (FLAIR) Signal Intensity Can Identify Stroke Within 6 and 8 Hours.
abstract: BACKGROUND
  Patients with wake-up or unknown time of onset stroke are usually excluded from recanalization. However, a few studies indicate that some magnetic resonance sequences can help predict time from symptom onset (SxO). Our goal was to assess the value of fluid-attenuated inversion recovery (FLAIR) signal intensity ratio (SIR) in identifying patients within 6 and 8 hours of stroke onset.
  
  
  METHODS
  We studied consecutive acute stroke patients with known time of onset who underwent magnetic resonance imaging (MRI) within 48 hours of SxO. SIR was calculated as the value of the FLAIR signal intensity of the identified area of infarction divided by the signal intensity in the homologous contralateral side of the brain.
  
  
  RESULTS
  Out of 160 patients included in this study, 72 and 80 patients had MRI within 6 and 8 hours of SxO, respectively. We found a positive correlation between SIR and time from SxO (Pearson coefficient, .63). Receiver operating characteristic curves indicated that SIR ≤ 1.18 could accurately identify patients within 6 hours of SxO (86% sensitivity, 79% specificity) and a SIR ≤ 1.20 can be identified within 8 hours (89% sensitivity, 76% specificity). Among patients with no visible FLAIR hyperintensity, 83% (95% CI, 77%-89%) were within the 6-hour window.
  
  
  CONCLUSIONS
  Quantitative assessment of FLAIR sequence can be used to identify patients within 6 and 8 hours of stroke onset.
authors.affiliation: College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: John
authors.initials: J
authors.lastname: Legge
authors.affiliation: College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Ada
authors.initials: A
authors.lastname: Graham
authors.affiliation: Department of Neurology, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Shailesh
authors.initials: S
authors.lastname: Male
authors.affiliation: College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: David
authors.initials: D
authors.lastname: Copeland
authors.affiliation: College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Richard
authors.initials: R
authors.lastname: Lee
authors.affiliation: Department of Neurology, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Nitin
authors.initials: N
authors.lastname: Goyal
authors.affiliation: Department of Neurology, University of Tennessee Health Science Center, Memphis, Tennessee; Department of Neurology, Geisinger Health System, Danville, Pennsylvania. Electronic address: rzand@uthsc.edu.
authors.forename: Ramin
authors.initials: R
authors.lastname: Zand
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D015203:Reproducibility of Results; D020521:Stroke / Q000000981:diagnostic imaging* / Q000628:therapy; D061665:Time-to-Treatment
keywords: Brain imaging; DWI; MRI; acute stroke; ischemic stroke; stroke onset; thrombectomy; thrombolysis