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FIG 1. A and B, Axial and coronal T2-weighted images (1.5 T, TR/TE = 3800/84 and 3500/75, respectively) show extensive areas of abnormally high signal intensity in the splenium and the perispenial, cingulate, and the bilateral perisplenial white matter. Note sparing of the hippocampi and the temporal and insular cortices. C–F, Diffusion-weighted images (upper row [C and E]) and corresponding apparent diffusion coefficient false-color maps (lower row) of week 8 (D) and week 26 (F) after disease onset. Note that the CSF signal intensity is nulled. C and D, Lesions on diffusion-weighted images 4 weeks after the first MR study (C) show hypointense central area with a hyperintense rim (arrows) and high regional mean diffusivity. E and F, Note resolution of diffusion-weighted hyperintensities and peripheral normalization of regional mean diffusivity, indicating irreversible necrosis and gliosis formation in areas with regional mean diffusivity exceeding about 1.4 x10-3 mm2/s, whereas initially hyperintense areas on diffusion-weighted images, mainly representing T2 shine-through, without corresponding reduction of regional mean diffusivity reflect potentially reversible inflammatory changes. (Image acquisition: TR/TE = 2200/120, tetrahedral gradient acquisition scheme [15] with b values of 330, 798, and 1320 s/mm2)
