HISTOPATHOLOGIC CORRELATES OF ABNORMAL WATER DIFFUSION IN CEREBRAL-ISCHEMIA - DIFFUSION-WEIGHTED MR-IMAGING AND LIGHT AND ELECTRON-MICROSCOPIC STUDY

PURPOSE: To correlate the findings on diffusion-weighted magnetic reso nance (MR) images with the cytologic and histologic findings in ischem ic tissue. MATERIALS AND METHODS: A photochemical model of cerebral in farction in rats was studied with diffusion- and T2-weighted MR imagin g. The development of lesions was followed from 20 minutes to 5 days a fter the onset of ischemia. Apparent water diffusion coefficient (ADC) maps were calculated and correlated with light and electron microscop ic findings. RESULTS: T2-weighted images clearly showed vasogenic edem a but did not enable distinction between areas with cellular damage an d the surrounding edematous regions. In contrast, the ADC, which was e levated in nonischemic edematous regions, was diminished in areas with histologic evidence of ischemic damage or necrosis. In the core of th e infarct, the ADC became elevated when electron microscopy revealed c ellular lysis. CONCLUSION: Diffusion-weighted images may help ascertai n the extent of cellular damage and death after stroke.