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Transient cell depolarization after permanent middle cerebral artery occlusion: An observation by diffusion‐weighted MRI and localized 1H‐MRS

Focal cerebral ischemia causes rapid intensity changes in diffusion‐weighted images (DWI) and elevated lactate as detected by localized proton spectroscopy (1H‐MRS). To investigate whether such changes can also be evoked by peri‐ischemic depolarizations, we combined DWI and 1H‐MRS measurements with DC potential recordings. About 40 min after occlusion of the middle cerebral artery in a rat, a negative DC deflection was observed indicating transient cell depolarization. Coincidentally with the depolarization a transient increase of the DWI signal intensity and a partially reversible increase of lactate occurred in the periphery of the ischemic territory. These results show that peri‐ischemic depolarization, known to contribute to the evolution of cerebral infarction, evokes disturbances that can be detected by DWI and 1H‐MRS.