Posterior reversible encephalopathy syndrome: Utility of fluid-attenuated inversion recovery MR imaging in the detection of cortical and subcortical lesions

BACKGROUND AND PURPOSE: Posterior reversible encephalopathy syndrome (PRES) is typically characterized by headache, altered mental functioning, seizur es, and visual loss associated with imaging findings of bilateral subcortic al and cortical edema with a predominantly posterior distribution. Our goal was to determine whether fluid-attenuated inversion recovery (FLAIR) imagi ng improves the ability to detect subtle peripheral lesions of PRES, as com pared with conventional MR techniques. METHODS: Sixteen patients with clinical and imaging findings consistent wit h PRES were studied. Thirteen patients had undergone transplantation and ha d cyclosporin A neurotoxicity. Fast-FLAIR images were compared with spin-ec ho proton density- and T2-weighted images. RESULTS: FLAIR imaging improved diagnostic confidence and conspicuity of th e T2 hyperintense lesions of PRES, typically in the subcortical white matte r of the parietooccipital regions bilaterally. On all 23 abnormal MR studie s, FLAIR was judged superior to proton density- and T2-weighted images for the detection of PRES in the supratentorial brain. In a mean of 6.7 of 23 s tudies, FLAIR findings prompted a raise in the grade of disease severity. F LAIR also showed cortical involvement in 94% of patients with PRES and in a mean of 46% of the total lesion burden. In four cases, subtle lesions were virtually undetectable without FLAIR. Brain stem or cerebellar disease was encountered in 56% of patients. CONCLUSION: FLAIR improves the ability to diagnose and detect subcortical a nd cortical lesions in PRES as compared with proton density- and T2-weighte d spin-echo images. We therefore believe that FLAIR should be performed in patients with suspected PRES to allow more confident recognition of the oft en subtle imaging abnormalities.