In vivo diffusion–perfusion magnetic resonance imaging of acute cerebral ischemia

Abstract

We compared the anatomic extent and severity of ischemic brain injury shown on diffusion-weighted magnetic resonance (MR) images, with cerebral tissue perfusion deficits demonstrated by a nonionic intravascular T2*-shortening magnetic susceptibility contrast agent used in conjunction with standard T2-weighted spin-echo and gradient-echo echo-planar images. Diffusion-weighted images displayed increased signal intensity in the vascular territory of the middle cerebral artery 25–40 min after permanent occlusion, whereas T2-weighted images without contrast were negative or equivocal for at least 2–3 h after stroke was induced. Contrast-enhanced T2-weighted and echo-planar images revealed perfusion deficits that were spatially closely related to the anatomic regions of ischemic tissue injury. These data indicate that diffusion-weighted MR images are very sensitive to early onset pathophysiologic changes induced by acute cerebral ischemia. Combined sequential diffusion–perfusion imaging enables noninvasive in vivo examination of the relationship between hypoperfusion and evolving ischemic brain injury.Key words: in vivo, diffusion, perfusion, acute cerebral ischemia, magnetic resonance imaging.