title: Atlas-based topographical scoring for magnetic resonance imaging of acute stroke.
abstract: OBJECTIVE
  The Alberta Stroke Program Early CT Score (ASPECTS), a 10-point scale, is a clinical tool for assessment of early ischemic changes after stroke based on the location and extent of a visible stroke lesion. It has been extended for use with MR diffusion-weighted imaging. The purpose of this work was to automate a MR topographical score (MR-TS) using a digital atlas to develop an objective tool for large-scale analyses and possibly reduce interrater variability and slice orientation differences.
  
  
  METHODS
  We assessed 30 patients with acute ischemic stroke with a diffusion lesion who provided informed consent. Patients were imaged by CT and MRI within 24 hours of symptom onset. An MR-TS digital atlas was generated using the ASPECTS scoring sheet and anatomic MR data sets. Automated MR topographical scores (auto-MR-TS) were obtained based on the overlap of lesions on apparent diffusion coefficient maps with MR-TS atlas regions. Auto-MR-TS scores were then compared with scores derived manually (man-MR-TS) and with conventional CT ASPECTS scores.
  
  
  RESULTS
  Of the 30 patients, 29 were assessed with auto-MR-TS. Auto-MR-TS was significantly lower than CT ASPECTS (P<0.001), but with a median difference of only 1 point. There was no significant difference between the auto-MR-TS and the man-MR-TS with a median difference of 0 points; 86% of patient scores differed by <or=1 point.
  
  
  CONCLUSIONS
  Auto-MR-TS provides a measure of stroke severity in an automated fashion and facilitates more objective, sensitive, and potentially more complex ASPECTS-based scoring.
authors.affiliation: Biomedical Engineering, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Robert K
authors.initials: RK
authors.lastname: Kosior
authors.forename: M Louis
authors.initials: ML
authors.lastname: Lauzon
authors.forename: Nikolai
authors.initials: N
authors.lastname: Steffenhagen
authors.forename: Jayme C
authors.initials: JC
authors.lastname: Kosior
authors.forename: Andrew
authors.initials: A
authors.lastname: Demchuk
authors.forename: Richard
authors.initials: R
authors.lastname: Frayne
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D020521:Stroke / Q000145:classification / Q000175:diagnosis*