Characterization of tumefactive demyelinating lesions using MR imaging and in-vivo proton MR spectroscopy.

BACKGROUND AND OBJECTIVES: Diagnosis of tumefactive demyelinating lesions (TDLs) is challenging to both clinicians and radiologists. Our objective in this study was to analyze and characterize these lesions clinically, biochemically, electrophysiologically, and on imaging. METHODS: A retrospective analysis with prospective follow-up of 18 cases of TDLs was performed. Imaging included T2-, T1-weighted, fluid-attenuated inversion recovery (FLAIR), post-contrast T1-weighted, diffusion weighted imaging (DWI), and proton magnetic resonance spectroscopy (PMRS). RESULTS: All the lesions appeared hyperintense on T2 and FLAIR images. Increased Apparent diffusion coefficient (ADC) (0.93-2.21 x 10(-3) mm(2)/s) in centre of the lesion was seen in 14/18 cases; however, peripheral restriction (ADC values 0.55-0.64 x 10(-3) mm(2)/s) was noted in 11/18 cases. In all, 13/18 cases showed contrast enhancement with open ring (n = 5), complete ring (n = 1), minimal (n = 4), and infiltrative (n = 3) pattern of enhancement. Nine of these 13 cases also showed venular enhancement. On PMRS, nine showed glutamate/glutamine (Glx) at 2.4 ppm. CONCLUSION: Clinical features along with several MRI characteristics such as open ring enhancement, peripheral restriction on DWI, venular enhancement, and presence of Glx on spectroscopy may be rewarding in differentiating TDLs from neoplastic lesions.