Fig. 1.

Representative patient images of the T2-FLAIR mismatch sign and tumour margins. The well-defined right fronto-insular tumour (a and b) demonstrates high T2 signal on T2-weighted imaging (left), with the majority of the lesion demonstrating substantially lower signal on FLAIR (middle), with a preserved FLAIR-hyperintense rim. In contrast, the right temporal tumour (c) in a different patient has ill-defined margins