[Diffusion-weighted MR tomography in focal cerebral ischemia: possibilities offered by a 1.0 Tesla clinical device]

To develop and to implement a fast, highly diffusion-weighted MR-sequence on a conventional 1 T MR scanner and to examine this sequence as to its capability of characterising tissue damage due to focal cerebral ischaemia.

Within a CE-FAST-sequence diffusion gradients were inserted in all gradient directions. By phantom measurements the maximal diffusion weighting was determined for different T1 and T2 values and flip angles. The optimised sequence was used for monitoring the diffusion of focal cerebral ischaemia in 14 rats following endovascular occlusion of the middle cerebral artery.

The ischaemic lesion could be easily visualised as a bright area in the images with high diffusion weighting. The mean relative decrease of the diffusion coefficient in the ischaemic brain parenchyma was 29%. The diffusion coefficient, decreased significantly with increasing occlusion time.

Our study suggests that the installed sequence is capable of producing highly diffusion weighted images without requiring a special gradient system. The sequence is potentially useful for monitoring cerebral ischaemia on the basis of calculating the change of the diffusion coefficient.