MRI of Toxic, Metabolic, and Autoimmune Encephalopathies: A Review

The brain is highly susceptible to toxins, autoimmune disorders, and metabolic changes, which can result in a broad range of encephalopathies. Signs are often nonspecific and can range from a hyper-alert agitated state, to coma, and death. Therefore, clinical assessment alone is often inconclusive. MR imaging is the modality of choice and frequently provides the first indication an encephalopathy as a possible cause of symptoms. By recognizing distinct imaging features, such as symmetry, characteristic topographic distribution, and enhancement patterns of the lesions, the radiologist plays a crucial role in narrowing the diagnosis to help improve patient outcome in an interdisciplinary approach.