Ex vivo MR microimaging of neuronal damage after kainate-induced status epilepticus in rat: Correlation with quantitative histology

The present study was designed to investigate whether T-2-weighted signal c hanges obtained by microimaging of paraformaldehyde-fixed brain correlate w ith the histologically quantified damage in a model of status epilepticus ( SE) induced by kainic acid in the rat. Animals were killed at several time points up to 8 weeks after a single intraperitoneal kainate (KA) injection (9 mg/kg). Perfusion-fixed brains were embedded in gelatin for MR microlmag ing at 9.4T. After the MRI analysis, the gelatin was removed and the brains were cryoprotected and processed for quantitative histology. Severity of n euronal damage and gliosis were assessed from thionin-stained serial sectio ns. Correlative analysis of microimaging and histology data was done in the hippocampus, amygdala, parietal rhinal cortex (PaRH), piriform cortex (Pir ), and entorhinal cortex. The relative signal intensities in T-2-weighted i mages correlate with the severity of neuronal damage in the matched histolo gical sections (correlation coefficients of 0.752-0.826). Our data show tha t MR microimaging ex vivo detects the degree of neuronal damage and its ana tomical distribution after KA-induced SE, thus providing a useful tool for detecting the dynamics of progressive neuronal damage after prolonged seizu res. (C) 2001 Wiley-Liss, Inc.