Gliomatosis cerebri in a 74-year-old woman. A, Axial T2-weighted, FLAIR, and enhanced Tl -weighted images demonstrate high signal intensity in the right temporal lobe involving white matter and cortex. The acute clinical presentation suggested infarct. B, Diffusion weighted image and TRACE apparent diffusion coefficient (ADC) map demonstrate increased water diffusion in the lesion (slightly higher values on ADC map, outlined by arrowheads), excluding acute infarction. Note that encephalitis may have a similar MR appearance and diffusion characteristics. (Click to magnify figure)

http://yassermetwally.files.wordpress.com/2008/03/abt8.jpg

Gliomatosis cerebri. Coronal FLAIR images show diffuse infiltration of the left temporal lobe with gray and white matter involvement (arrowhead). Note the relative lack of mass effect for the degree of infiltration. The white matter infiltration extends across the corpus callosum (white arrow) and involves bilateral deep white matter tracts (double arrow). (Click to magnify figure)

http://yassermetwally.wordpress.com/brain-tumors/adult-brain-tumors/