Metachromatic leukodystrophy. Diffusion MR imaging and proton MR spectroscopy.

Metachromatic leukodystrophy is characterized by dysmyelination caused by a deficiency of arylsulfatase-A. In a 17-month-old boy with metachromatic leukodystrophy, an echo-planar diffusion MR sequence revealed a restricted diffusion pattern in the deep white matter, manifested by high-signal on b=1000 s/mm2 images, and low ADC values (0.56 x 10(-3) mm2/s). Proton MR spectroscopy revealed a marked decrease in choline, a metabolite related to myelin turnover. These observations consisting of a restricted diffusion pattern on diffusion MR imaging, and decreased choline peaks on proton spectroscopy, likely represented dysmyelination in metachromatic leukodystrophy.