Methotrexate-induced Leukoencephalopathy without Typical Restricted Diffusion on Diffusion-weighted Imaging and the Utility of Magnetic Resonance Spectroscopy to Support the Diagnosis

Methotrexate (MTX) is a common antimetabolite agent that is widely used today in treating leukemia, lymphoma, and osteosarcoma. Its use has been associated with leukoencephalopathy causing seizures, paralysis, and even coma. To achieve the best possible outcome, it is important to be able to make a prompt diagnosis. Studies reported restricted diffusion on diffusion-weighted imaging (DWI) which is a reliable early sign of acute MTX-induced leukoencephalopathy. However, we report here the first case of MTX-induced leukoencephalopathy without typical restricted diffusion on DWI and the utility magnetic resonance spectroscopy to support this diagnosis in the difficult case such as the one being presented here.