Multinodular and vacuolating neuronal tumor: magnetic resonance imaging features

Objective: Multinodular and vacuolating neuronal tumors (MVNT) are rare, usually incidental findings in the cerebral cortex. We report a series of patients to illustrate the spectrum of MR imaging appearances of MVNT in a routine clinical setting. Materials and methods: This is a retrospective analysis of patients with radiologic features suggestive of MVNT. Lesion location, size, and morphology; signal characteristics in conventional sequences, diffusion-weighted sequences, and susceptibility-weighted imaging; presence of contrast enhancement; and metabolic patterns observed using magnetic resonance spectroscopy were analyzed. Histopathological diagnosis was available for three patients. Results: We identified ten patients (six women and four men; median age, 30 years [range, 21–43 years]). The lesions were predominantly localized in the left hemisphere and parietal lobe. The size of the lesions ranged from 15 to 45 mm. All lesions were hypointense on T1-weighted images and hyperintense on T2/FLAIR images, with a multinodular and bubble-like pattern on MRI. None of the lesions had associated edema, mass effect, or contrast enhancement. Variable signal intensities were observed on diffusion-weighted images; however, the apparent diffusion coefficient maps uniformly indicated facilitated diffusion. Susceptibility-weighted imaging showed focal hypointensity in only one patient. The magnetic resonance spectroscopy results varied from normal spectra to mild elevation of choline and lactate peak elevation. One patient had an associated pilomyxoid astrocytoma. The histopathological changes were those of the MVNT. Conclusions: Although MVNTs tend to have a typical morphology on conventional MRI, advanced imaging features are variable and can sometimes mimic other pathologies. Familiarity with this imaging spectrum will help prevent unwarranted workups and therapy.