title: Are the current MRI criteria using the DWI-FLAIR mismatch concept for selection of patients with wake-up stroke to thrombolysis excluding too many patients?
abstract: BACKGROUND
  Up to 25% of stroke patients wake up with a neurological deficit, so called wake-up stroke (WUS). Different imaging approaches that may aid in the selection of patients likely to benefit from reperfusion therapy are currently under investigation. The magnetic resonance imaging (MRI) diffusion weighted imaging - fluid attenuated inversion recovery (DWI-FLAIR) mismatch concept is one proposed method for identifying patients presenting within 4.5 hours of the ischemic event.
  
  
  OBJECTIVE
  To report our experience with the DWI-FLAIR mismatch concept for selection of wake-up stroke patients to be thrombolysed at our centre.
  
  
  METHODS
  Patients treated with off label intravenous thrombolysis (IVT) for WUS at our centre during a 6.5-month period were included. We performed MRI including DWI and FLAIR in all patients at admission. Each MRI examination was rated as either DWI-FLAIR mismatch or match. National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale were used to measure clinical outcome. Cerebral computed tomography (CT) or MRI was performed within 24 hours after thrombolysis to determine the presence of any intracranial haemorrhage (ICH).
  
  
  RESULTS
  Ten patients treated with IVT for WUS were included. Four patients had a DWI-FLAIR mismatch and after IVT treatment the mean reduction in NIHSS in the DWI-FLAIR mismatch group was 4.0. In the DWI-FLAIR match group the mean reduction in NIHSS after IVT therapy was 4.8. None of the ten patients had any signs of ICH on follow-up imaging.
  
  
  CONCLUSIONS
  In this small series DWI-FLAIR mismatch was not associated with worse outcome or ICH. This suggests that selecting WUS patients using DWI-FLAIR mismatch in clinical trials may exclude a large group of patients who might benefit.
authors.affiliation: Department of Radiology, Stavanger University Hospital, Postboks 8100, 4068, Stavanger, Norway. audun.odland@sus.no.|Faculty of Medicine, University of Oslo, Oslo, Norway. audun.odland@sus.no.
authors.forename: Audun
authors.initials: A
authors.lastname: Odland
authors.affiliation: Department of Radiology, Stavanger University Hospital, Postboks 8100, 4068, Stavanger, Norway. pal.hervik.servoll@sus.no.
authors.forename: Pål
authors.initials: P
authors.lastname: Særvoll
authors.affiliation: Department of Neurology, Stavanger University Hospital, Stavanger, Norway. rajiv.kishu.advani@sus.no.|Neuroscience Research Group, Stavanger University Hospital, Stavanger, Norway. rajiv.kishu.advani@sus.no.
authors.forename: Rajiv
authors.initials: R
authors.lastname: Advani
authors.affiliation: Department of Neurology, Stavanger University Hospital, Stavanger, Norway. friedrich.martin.wilhelm.kurz@sus.no.|Neuroscience Research Group, Stavanger University Hospital, Stavanger, Norway. friedrich.martin.wilhelm.kurz@sus.no.
authors.forename: Martin W
authors.initials: MW
authors.lastname: Kurz
authors.affiliation: Department of Radiology, Stavanger University Hospital, Postboks 8100, 4068, Stavanger, Norway. kathinka.dehli.kurz@sus.no.
authors.forename: Kathinka D
authors.initials: KD
authors.lastname: Kurz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D012189:Retrospective Studies; D012890:Sleep; D020521:Stroke / Q000175:diagnosis* / Q000628:therapy*; D015912:Thrombolytic Therapy; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome