Differential diagnosis of restricted diffusion confined to the cerebral cortex

Diffusion-weighted MRI (DWI) has become increasingly widely available over recent years and is recognized as a powerful tool in neuroimaging. It is primarily used to identify acute ischaemia in patients presenting with stroke because of the improved sensitivity it offers early in the course of the disease. DWI also contributes useful diagnostic information in a range of other conditions. In this review we describe the magnetic resonance imaging (MRI) features of a number of conditions characterized by cortical diffusion restriction (CDR).