High b-value diffusion-weighted imaging of acute brain infarction

High b-value diffusion-weighted (DW) imaging obtained with a b-value of 2,000 s/mm(2) offers theoretical advantages over DW imaging obtained with a b-value of 1,000 s/mm(2) for detection of acute brain infarction. The purpose of this study was to determine whether high b-value DW images (b=2,000) are better than b=1,000 images for detection of diffusion change in patients with acute brain infarction. We compared diffusion-weighted (DW) images obtained with a b-value of 1,000 s/mm(2) with those obtained with a b-value of 2,000 s/mm(2) in 84 patients with small lesions (brain stem infarction, lacuna infarction) examined within 24 hours of clinical onset. Qualitative analysis was performed concerning lesion conspicuity. In quantitative analysis, contrast ratios (CR) were measured and findings of b=1,000 and b=2,000 images were compared. False-negative rate of b=1,000 and b=2,000 images were 23.8% and 3.6%, respectively, relative to the presense or absense of infarction on the follow-up MR or CT images. On qualitative analysis, lesions were more conspicuous on b=2,000 images. On quantitative analysis, as the b-value increased, mean CR increased. DW images aquired with a b-value of 2,000 s/mm(2) Were better than DW images aquired with a b-value of 1,000 s/mm(2) for detection of diffusion change in patients with acute brain infarction.