DIFFUSION-WEIGHTED MR IMAGING OF ACUTE STROKE - CORRELATION WITH T2-WEIGHTED AND MAGNETIC SUSCEPTIBILITY-ENHANCED MR IMAGING IN CATS

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  • 1 May 1990
    • journal article
    • research article
    • Vol. 11  (3) , 423-429
Abstract
We evaluated the temporal and anatomic relationships between changes in diffusion-weighted MR image signal intensity, induced by unilateral occlusion of the middle cerebral artery in cats, and tissue perfusion deficits observed in the same animals on T2-weighted MR images after administration of a nonionic intravascular T2* shortening agent. Diffusion-weighted images obtained with strong diffusion-sensitizing gradient strengths (5.6 gauss/cm, corresponding to gradient attenuation factor, b, values of 1413 sec/mm2) displayed increased signal intensity in the ischemic middle cerebral artery territory less than 1 hr after occlusion, whereas T2-weighted images without contrast usually failed to detect injury for 2-3 hr after stroke. After contrast administration (0.5-1.0 mmol/kg Dy-DTPA-BMA, IV), however, T2-weighed images revealed perfusion deficits (relative hyperintensity) within 1 hr after middle cerebral artery occlusion that corresponded closely to the anatomic regions of ischemic injury shown on diffusion-weighted MR images. Close correlations were also found between early increases in diffusion-weighted MR image signal intensity and disrupted phosphorus-31 and proton metabolite levels evaluated with surface coil MR spectroscopy, as well as with post-mortem histopathology. These data indicate that diffusion-weighted MR images more accurately reflect early-onset pathophysiologic changes induced by acute cerebral ischemia than do T2-weighted spin-echo images.