title: Limited versus Whole-Brain Perfusion for the Indication of Thrombolysis in the Extended Time Window of Acute Cerebral Ischemia.
abstract: BACKGROUND
  Perfusion computed tomography (PCT) has emerged as alternative to magnetic resonance imaging (MRI) for assessment of patients clinically qualifying for off-label thrombolysis within 4.5 to 9 hours after onset of ischemic stroke. However, disadvantage of PCT is its often limited anatomic coverage with only 2 or 3 slices when using a 4- to 64-section scanner. Our purpose was therefore to evaluate the value of 2- and 3-slice perfusion compared to whole-brain perfusion.
  
  
  METHODS
  One hundred twenty-five patients undergoing MRI beyond 4.5 hours after symptom onset with supratentorial perfusion deficit were selected retrospectively. Accordingly to PCT slice positioning, 2 or 3 slices of the whole-brain perfusion weighted imaging data set were depicted. Volumes of infarct (using cerebral blood volume) and penumbra (using time-to-peak and cerebral blood volume) were calculated, and results were compared with 2- and 3-slice-derived volumes, respectively.
  
  
  RESULTS
  Whole-brain imaging revealed a mismatch of more than 20% in 68.8% of patients (defined as 100%). Two-slice imaging detected a perfusion deficit in 72% and a mismatch in 48.8% (sensitivity = 70.9%). Three-slice imaging detected a perfusion deficit in 76% and a mismatch in 50.4% (sensitivity = 73.3%). Although there was no significant difference between 2- and 3-slice imaging (P > .23), both techniques revealed significantly less patients with mismatch compared to whole-brain coverage (P < .01).
  
  
  CONCLUSIONS
  Two- and 3-slice imaging like obtained with PCT on most installed CT systems to assess perfusion deficits with subsequent mismatch calculation in acute stroke outside the 4.5-hour time window is significantly inferior to whole-brain coverage and, hence, has to be considered as a less-than-ideal solution.
authors.affiliation: Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany. Electronic address: lorenz.breuer@uk-erlangen.de.
authors.forename: Lorenz
authors.initials: L
authors.lastname: Breuer
authors.affiliation: Department of Neuroradiology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Knott
authors.affiliation: Department of Neuroradiology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Struffert
authors.affiliation: Department of Neuroradiology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Kloska
authors.affiliation: Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Natalia
authors.initials: N
authors.lastname: Kurka
authors.affiliation: Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schwab
authors.affiliation: Department of Neuroradiology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Arnd
authors.initials: A
authors.lastname: Dörfler
authors.affiliation: Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Köhrmann
authors.affiliation: Department of Neuroradiology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Engelhorn
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology*; D002545:Brain Ischemia / Q000209:etiology / Q000628:therapy*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging; D012189:Retrospective Studies; D020521:Stroke / Q000150:complications; D015912:Thrombolytic Therapy / Q000379:methods*; D013997:Time Factors
keywords: Ischemic stroke; extended time window; limited brain perfusion; stroke imaging