Figure 2. (a) Axial T₂ weighted and (b) coronal T₁ weighted images in a patient with progressive multifocal leucoencephalopathy. There is high T2 and low T1 signal white matter abnormality in the right frontal region that extends along the gyral core, with preservation of the grey matter. (c) Coronal T₁ weighted image of the same patient shows the low T1 signal to extend along the white matter tracts, through theright internal capsule to the cerebral peduncle. Incidental note is made of agenesis of the corpus callosum.