Dynamics of cerebral injury, perfusion, and blood-brain barrier changes after temporary and permanent middle cerebral artery occlusion in the rat

By means of magnetic resonance imaging (MRI) we longitudinally monitored th e evolution of ischemic injury, changes in cerebral hemodynamics and altera tions of the blood-brain barrier (BBB) during permanent or temporary middle cerebral artery occlusion (MCAO) in rats. Using the intraluminal suture oc clusion model, male Sprague-Dawley rats were subjected to either permanent MCAO (Group A, n=6), reperfusion after 1 h (Group B, n=5), or reperfusion a fter 3 h (Group C, n=5). Diffusion- and perfusion-weighted MRI and Gd-DTPA enhanced T1-weighted images were performed at six time points from 0.5 to 6 h post-MCAO. The lesion volume increased progressively in group A, decreas ed significantly in group B (P<0.01), and only showed a tendency toward red uction in group C. Perfusion-weighted MRI delineated severe perfusion defic its in the ischemic core, confirmed early and late reperfusion, and was abl e to demonstrate postischemic hyperperfusion in group C. Gd-DTPA extravasat ion was found in all animals with permanent MCAO and initially became gross ly visible between 4.5 and 6 h post-MCAO. While only 2 animals demonstrated contrast enhancement in group B, widespread BBB changes were detected imme diately following late reperfusion (Group C). Our results demonstrate that with advanced MRI techniques, alterations of the BBB can be correlated with the hemodynamic and biophysical consequences of reperfusion. (C) 1999 Else vier Science B.V. All rights reserved.