Global forebrain ischemia in the Mongolian gerbil is a common animal model for use in stroke research. We produced lesions of graded severity in gerbil brains (after prescreening by MR imaging) by performing 6-minute bilateral carotid artery occlusions while monitoring pericranial temperature with a temporalis muscle thermocouple probe and maintaining the temperature at 32 degrees C, 36 degrees C, or 40 degrees C. Lesion severity was scored 4 days after occlusion from findings on spin-echo images acquired at 7 T and from histologic scores. Statistically significant correlation was observed between the MR imaging score and brain temperature and between the MR imaging score and the area of the CA region of the hippocampus measured by histology. In addition, because prescreening with MR imaging revealed abnormalities in the hippocampus of some of the animals, and these animals were rejected from the study, the statistical significance of the result could be strengthened.