title: Evolution of hyperacute stroke over 6 hours using serial MR perfusion and diffusion maps.
abstract: OBJECTIVE
  To develop an appropriate method to evaluate the time-course of diffusion and perfusion changes in a clinically relevant animal model of ischemic stroke and to examine lesion progression on MR images. An exploration of acute stroke infarct expansion was performed in this study by using a new methodology for developing time-to-infarct maps based on the time at which each voxel becomes infarcted. This enabled definition of homogeneous regions from the heterogeneous stroke infarct.
  
  
  METHODS
  Time-to-infarct maps were developed based on apparent diffusion coefficient (ADC) changes. These maps were validated and then applied to blood flow and time-to-peak maps to examine perfusion changes.
  
  
  RESULTS
  ADC stroke infarct showed different evolution patterns depending on the time at which that region of tissue infarcted. Applying the time-to-infarct maps to the perfusion maps showed localized perfusion evolution characteristics. In some regions, perfusion was immediately affected and showed little change over the experiment; however, in some regions perfusion changes were more dynamic.
  
  
  CONCLUSIONS
  Results were consistent with the diffusion-perfusion mismatch hypothesis. In addition, characteristics of collateral recruitment were identified, which has interesting stroke pathophysiology and treatment implications.
authors.affiliation: Seaman Family MR Research Centre, Foothills Medical Centre, University of Calgary, Alberta, Canada.
authors.forename: Ashley D
authors.initials: AD
authors.lastname: Harris
authors.forename: Robert K
authors.initials: RK
authors.lastname: Kosior
authors.forename: Henry S
authors.initials: HS
authors.lastname: Chen
authors.forename: Linda B
authors.initials: LB
authors.lastname: Andersen
authors.forename: Richard
authors.initials: R
authors.lastname: Frayne
mesh_terms: D000818:Animals; D001931:Brain Mapping / Q000379:methods*; D002560:Cerebrovascular Circulation; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004195:Disease Models, Animal; D018450:Disease Progression; D004285:Dogs; D019786:Gadolinium DTPA; D007091:Image Processing, Computer-Assisted; D020521:Stroke / Q000473:pathology*; D013997:Time Factors
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA