MONITORING THE INITIAL EXPANSION OF FOCAL ISCHEMIC CHANGES BY DIFFUSION-WEIGHTED MRI USING A REMOTE-CONTROLLED METHOD OF OCCLUSION

The purpose of the present study was to quantify the early changes whi ch occur on diffusion-weighted imaging following focal cerebral ischae mia. We have developed a method for the remote occlusion of the middle cerebral artery in the rat, allowing early changes to be monitored an d images to be acquired before and after ischaemia under identical con ditions. Sequential diffusion-weighted images were acquired before and for up to 6 h following the occlusion. The data show that a hyperinte nse area appears soon after occlusion which expands during the first 2 h. It has previously been shown that the hyperintensity observed afte r ischaemia is linked to events associated with energy failure. Our fi ndings are in good agreement with previous pathophysiological studies of focal ischaemia, which suggest a growing of the energy depleted are a. In conclusion, our data extend the usefulness of diffusion-weighted imaging to the study of the early spatial evolution of the mast compr omised area after focal ischaemia. Diffusion-weighted imaging may cons titute a very powerful tool to investigate pharmacological therapies w hich may interact with this evolution, both in experimental and clinic al studies.