Evolution of hyperacute stroke over 6 hours using serial MR perfusion and diffusion maps.
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.
Harris
Ashley D
AD
Seaman Family MR Research Centre, Foothills Medical Centre, University of Calgary, Alberta, Canada.
Kosior
Robert K
RK
Chen
Henry S
HS
Andersen
Linda B
LB
Frayne
Richard
R
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
D003287:Contrast Media; D019786:Gadolinium DTPA