title: Do FLAIR vascular hyperintensities beyond the DWI lesion represent the ischemic penumbra?
abstract: OBJECTIVE
  In acute stroke with proximal artery occlusion, FLAIR vascular hyperintensities observed beyond the boundaries of the cortical lesion on DWI (newly defined "FLAIR vascular hyperintensity-DWI mismatch") may be a marker of tissue at risk of infarction. Our aim was to compare the occurrence of FLAIR vascular hyperintensity-DWI mismatch relative to that of perfusion-weighted imaging-DWI mismatch in patients with proximal MCA occlusion before IV thrombolysis.
  
  
  METHODS
  In 141 consecutive patients with proximal MCA occlusion, 2 independent observers analyzed FLAIR images for the presence of FLAIR vascular hyperintensity-DWI mismatch before IV thrombolysis. PWI-DWI mismatch was defined as Volumehypoperfusion > 1.8 × VolumeDWI, with Volumehypoperfusion > 6 seconds on time to maximum value of the residue function maps in the 94 patients with available PWI. The presence of FLAIR vascular hyperintensity-DWI mismatch, PWI-DWI mismatch, and infarct growth on 24-hour follow-up DWI was compared.
  
  
  RESULTS
  A FLAIR vascular hyperintensity-DWI mismatch was present in 102/141 (72%) patients, with an excellent interobserver reliability (κ = 0.91), and a PWI-DWI mismatch, in 61 of the 94 (65%) patients with available PWI. FLAIR vascular hyperintensity-DWI mismatch predicted PWI-DWI mismatch with a sensitivity of 92% (95% CI, 85%-99%) and a specificity of 64% (95% CI, 47%-80%). Patients with FLAIR vascular hyperintensity-DWI mismatch had smaller initial DWI lesion and larger infarct growth (P < .001) than patients without FLAIR vascular hyperintensity-DWI mismatch, even though their final infarcts remained smaller (P < .001).
  
  
  CONCLUSIONS
  Albeit being moderately specific, probably due to inclusion of oligemic tissue, the FLAIR vascular hyperintensity-DWI mismatch identifies large PWI-DWI mismatch with high sensitivity.
authors.affiliation: From the Departments of Radiology (L.L., M.T., O.N., M.E., C.M., J.-F.M., C.O.).
authors.forename: L
authors.initials: L
authors.lastname: Legrand
authors.affiliation: From the Departments of Radiology (L.L., M.T., O.N., M.E., C.M., J.-F.M., C.O.).
authors.forename: M
authors.initials: M
authors.lastname: Tisserand
authors.affiliation: Neurology (G.T., J.-L.M, J.-C.B.), Université Paris Descartes Sorbonne Paris Cité, Centre de Psychiatrie et Neurosciences, Institut National de la Santé et de la Recherche Médicale S894, Centre Hospitalier Sainte-Anne, Paris, France.
authors.forename: G
authors.initials: G
authors.lastname: Turc
authors.affiliation: From the Departments of Radiology (L.L., M.T., O.N., M.E., C.M., J.-F.M., C.O.).
authors.forename: O
authors.initials: O
authors.lastname: Naggara
authors.affiliation: From the Departments of Radiology (L.L., M.T., O.N., M.E., C.M., J.-F.M., C.O.).
authors.forename: M
authors.initials: M
authors.lastname: Edjlali
authors.affiliation: From the Departments of Radiology (L.L., M.T., O.N., M.E., C.M., J.-F.M., C.O.).
authors.forename: C
authors.initials: C
authors.lastname: Mellerio
authors.affiliation: Neurology (G.T., J.-L.M, J.-C.B.), Université Paris Descartes Sorbonne Paris Cité, Centre de Psychiatrie et Neurosciences, Institut National de la Santé et de la Recherche Médicale S894, Centre Hospitalier Sainte-Anne, Paris, France.
authors.forename: J-L
authors.initials: JL
authors.lastname: Mas
authors.affiliation: From the Departments of Radiology (L.L., M.T., O.N., M.E., C.M., J.-F.M., C.O.).
authors.forename: J-F
authors.initials: JF
authors.lastname: Méder
authors.affiliation: Neurology (G.T., J.-L.M, J.-C.B.), Université Paris Descartes Sorbonne Paris Cité, Centre de Psychiatrie et Neurosciences, Institut National de la Santé et de la Recherche Médicale S894, Centre Hospitalier Sainte-Anne, Paris, France.
authors.forename: J-C
authors.initials: JC
authors.lastname: Baron
authors.affiliation: From the Departments of Radiology (L.L., M.T., O.N., M.E., C.M., J.-F.M., C.O.) c.oppenheim@ch-sainte-anne.fr.
authors.forename: C
authors.initials: C
authors.lastname: Oppenheim
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D020521:Stroke / Q000097:blood* / Q000473:pathology