Differential diagnosis by unenhanced FLAIR T2-weighted magnetic resonance images between solitary high grade gliomas and cerebral metastases appearing as contrast-enhancing cortico-subcortical lesions

The aim was to assess the value of unenhanced fluid-attenuated inversion recovery T2-weighted sequences (FLAIR-T2) in the differential diagnosis between solitary high-grade gliomas (HGG) and cerebral metastases (CM) appearing as contrast-enhancing cortico-subcortical lesions of the brain. In 69 patients with a contrast-enhancing cortico-subcortical brain lesion (43 HGG, and 26 CM), unenhanced FLAIR-T2 and gadolinium-enhanced FLAIR T1-weighted (Gd-FLAIR-T1) axial images have been reviewed for the involvement of the cortex adjacent to the contrast-enhancing lesion. In 27 (62.79%) out of 43 HGG, and 3 (11.53%) out of 26 CM, the cortex adjacent to the contrast-enhancing lesion showed high signal intensity on unenhanced FLAIR-T2 without enhancement at Gd-FLAIR-T1. Fischer's exact probability test was P = 0.0003 when applied to HGG versus CM categories, indicating a significant difference. The high signal intensity on unenhanced FLAIR-T2 without gadolinium-enhancement of the cortex adjacent to the enhancing lesion is more frequently associated with HGG than CM.