Magnetic Resonance Imaging Characteristics of Tumefactive Demyelinating Lesions

Tumefactive demyelinating lesions (TDLs) are often misdiagnosed as brain tumors. To identify imaging characteristics of TDLs for their proper diagnosis, their differences from malignant gliomas, etc., were investigated based on 3-Tesla magnetic resonance imaging (MRI) and MR spectroscopy data that was obtained from 5 patients diagnosed with TDLs in our hospital. MRI displayed a paraventricular lesion with a maximum diameter of ≥2 cm. Diffusion-weighted imaging (DWI) displayed a region of bright signal intensity at the margin of the lesion, and apparent diffusion coefficient (ADC) imaging displayed high signal intensity at the core of the lesion. The mass effect was mild relative to the size of the lesion, and the edema around the lesion was mild to moderate. Gadolinium-enhanced MRI displayed a characteristic open-ring sign, in which the ring of enhancement was incomplete (open towards the cortex), with the medullary vein running through the lesion, resulting in the enhancement of the surrounding area. MR spectroscopy displayed an increase in the choline peak, a decrease in the N-acetyl aspartate (NAA) peak, the presence of lactate/lipid peaks, and the presence of β, γ-glutamate-glutamine (GLX) peaks that are slightly shifted to a higher resonance frequency (2.1 2.4 ppm) from the NAA peak. Taken together, the following main characteristics were identified as imaging features of TDLs: bright rim on DWI, a high signal core on ADC imaging, an open-ring sign, and β, γ-GLX peaks on proton MR spectroscopy. We concluded that the key to the improvement of neurological symptoms of patients is the prompt initiation of steroid treatment following the accurate diagnosis of TDLs.