Methotrexate is a cause of acute neurotoxicity in children with hematologic malignancies. Patients most commonly present with acute onset of hemiplegia or aphasia, often 6-11 days after intrathecal methotrexate administration. Classic imaging finding is restricted diffusion in bilateral or unilateral centrum semiovale. Follow-up imaging in 1-2 months usually shows resolution of diffusion abnormality and development of abnormal signal intensity on FLAIR and T2WI.