NMR imaging of acute experimental cerebral ischemia: time course and pharmacologic manipulations.

Nuclear magnetic resonance (NMR) imaging was used to evaluate the intracerebral changes over time in gerbils after unilateral carotid artery ligation. Each animal was imaged during one of three stated periods 3-28 hr after surgery and again after administration of dexamethasone, morphine, or naloxone, agents reported to affect the clinical outcome of ischemic cerebral lesions. Asymptomatic animals exhibited no differences between the occluded and control hemispheres in relative signal intensity or in T1 or T2 relaxation times, but symptomatic animals demonstrated significant differences in these parameters between hemispheres. The ischemic lesion was detected at the earliest imaging time, 3 hr after surgery. A linear increase was observed in the relative interhemispheric signal intensity in three of four intensity images and in T1 and T2 relaxation times over the 24 hr experiment. No effect was noted on any image parameter as a result of pharmacologic manipulations. The results suggest that NMR may be of significant diagnostic importance for acute cerebral ischemia and infarction in man.