[en] We present magnetic resonance (MR) and 1H magnetic resonance spectroscopy (MRS) imaging alterations in four HIV-infected patients with progressive multifocal leukoencephalopathy (PML). In three of those subjects, changes typical of PML imaging were disclosed. MRS examinations showed a decrease in N-acetylaspartate content as well as an increase in choline and myoinositol content with presence of lactate and lipids signals. In one case of atypical MR image, MR spectroscopy confirmed PML diagnosis. The influence of antiretroviral treatment on central nervous system imaging as well as prognostic aspects of MR and MRS in subjects with progressive multifocal leukoencephalopathy are discussed. (author)