MRI - AIDS, progressive multifocal leukoencephalopathy: This 35-year-old woman with advanced AIDS and a history of pneumocystis carinii pneumonia presented with gradual decline in her gait and difficulty swallowing. Examination revealed moderate dysarthria, increased jaw jerk, right-sided hemiparesis and bilateral hyperreflexia. The FLAIR-weighted coronal MR images show high signal intensity within the right cerebellum, right midbrain, subcortical right temporal lobe and subcortical left parietal lobe. The lesions show no mass effect and, on additional views, exhibit no contrast enhancement.