28-year-old female with multiple sclerosis on Tysabri. Evaluate for PML. Again seen are multiple T2 hyperintense foci scattered about the periventricular, subcortical and deep white matter of the cerebrum as well as the corpus callosum, where many of the lesions are oriented perpendicular to the callososeptal interface. Many of these foci demonstrate corresponding T1 hypointensity. There is no significant change in these lesions. No new lesions.No restricted diffusion or susceptibility abnormalities. No intracranial mass or mass effect. No findings to suggest progressive multifocal leukoencephalopathy. The CSF spaces are appropriate for the patient's stated age with no midline shift. Vascular flow voids are preserved. Calvarium and external cranial soft tissues unremarkable.
No significant interval change in the multiple T2/FLAIR hyperintense foci throughout the subcortical and periventricular white matter consistent with known demyelinating disease. No new lesions. No findings suggest progressive multifocal leukoencephalopathy.