[High b value diffusion-weighted imaging of the brain: evaluation of usefulness]

We assessed the usefulness of higher b values during diffusion-weighted imaging. When the b value was changed in a stepwise manner from 1000 s/mm(2) to 2000, and then 3000, the signal intensities of the region showing a high signal on the images were reduced by 39% and 55%, respectively. When they were compared with the intensities on the normal sides, they were increased by 29% and 40%, respectively, suggesting improvement in the detectability of cerebral infarction. The values of the apparent diffusion coefficient were reduced 15% and 31%, respectively. When they were compared with the values on the normal sides, the values were almost equivalent regardless of the b value.