Advanced multiparametric magnetic resonance imaging of multinodular and vacuolating neuronal tumor.

BACKGROUND AND PURPOSE: Multinodular and vacuolating neuronal tumor (MVNT) of the cerebrum is a rare brain lesion with suggestive imaging features. The aim of our study was to report the largest series of MVNTs so far and to evaluate the utility of advanced multiparametric magnetic resonance (MR) techniques. METHODS: This multicenter retrospective study was approved by our institutional research ethics board. From July 2014 to May 2019, two radiologists read in consensus the MR examinations of patients presenting with a lesion suggestive of an MVNT. They analyzed the lesions' MR characteristics on structural images and advanced multiparametric MR imaging. RESULTS: A total of 64 patients (29 women and 35 men, mean age 44.2 ± 15.1 years) from 25 centers were included. Lesions were all hyperintense on fluid-attenuated inversion recovery and T2-weighted imaging without post-contrast enhancement. The median relative apparent diffusion coefficient on diffusion-weighted imaging was 1.13 [interquartile range (IQR), 0.2]. Perfusion-weighted imaging showed no increase in perfusion, with a relative cerebral blood volume of 1.02 (IQR, 0.05) and a relative cerebral blood flow of 1.01 (IQR, 0.08). MR spectroscopy showed no abnormal peaks. Median follow-up was 2 (IQR, 1.2) years, without any changes in size. CONCLUSIONS: A comprehensive characterization protocol including advanced multiparametric magnetic resonance imaging sequences showed no imaging patterns suggestive of malignancy in MVNTs. It might be useful to better characterize MVNTs.

Multinodular and Vacuolating Posterior Fossa Lesions of Unknown Significance.

Multinodular and vacuolating neuronal tumor of the cerebrum is a rare supratentorial brain tumor described for the first time in 2013. Here, we report 11 cases of infratentorial lesions showing similar striking imaging features consisting of a cluster of low T1-weighted imaging and high T2-FLAIR signal intensity nodules, which we referred to as multinodular and vacuolating posterior fossa lesions of unknown significance. No relationship was found between the location of the lesion and clinical symptoms. A T2-FLAIR hypointense central dot sign was present in images of 9/11 (82%) patients. Cortical involvement was present in 2/11 (18%) of patients. Only 1 nodule of 1 multinodular and vacuolating posterior fossa lesion of unknown significance showed enhancement on postcontrast T1WI. DWI, SWI, MRS, and PWI showed no malignant pattern. Lesions did not change in size or signal during a median follow-up of 3 years, suggesting that multinodular and vacuolating posterior fossa lesions of unknown significance are benign malformative lesions that do not require surgical intervention or removal.

[Imaging of a thickened-wall gallbladder]. / Imagerie des épaississements de la paroi vésiculaire.

Thickening of the gallbladder wall may result from a large spectrum of pathological conditions, intrinsic as well as extrinsic to the biliary tract, and may have different appearances. Accurate diagnosis is usually established after a correlation of imaging findings, laboratory data and clinical history. US remains the initial imaging modality for the evaluation of acute right upper quadrant pain. CT and MRI are complementary to US and have an increasing role in assessing a thickened-wall gallbladder.

Endocrine pancreatic tumours and helical CT: contrast enhancement is correlated with microvascular density, histoprognostic factors and survival.

PURPOSE: To assess the role of contrast-enhanced helical CT in the evaluation of tumour vascularity in endocrine pancreatic tumours (EPTs), and to determine the predictive factors of malignancy of EPTs at helical CT with CT-histopathological correlation. MATERIALS AND METHODS: Thirty-seven consecutive patients with histopathologically proven EPTs underwent dual-phase helical CT. For each tumour detected, its density relative to the surrounding parenchyma was scored on the pancreatic phase using a 5-point scale. Radiological findings were correlated with histopathological (vessel density count) and clinical follow-up findings. RESULTS: Thirty of 37 patients had non-functioning EPTs and overall 44 tumours were detected by helical CT (mean size 38, range 5-100 mm). CT showed calcifications in 10 tumours. Calcifications were associated with well-differentiated carcinomas (90%, p = 0.02). Vascular density assessed by light microscopy was significantly correlated with tumour enhancement at the pancreatic phase (p = 0.0001). Poorly differentiated carcinomas were less vascularised than well-differentiated tumours and carcinomas (34 vs. 264 vessels/mm2, p = 0.0073). Tumour differentiation also correlated with tumour enhancement at the pancreatic phase (p = 0.0044, trend test): poorly differentiated carcinomas were hypoattenuating (71%) and isoattenuating or weakly hyperattenuating (29%), compared with well-differentiated carcinomas and tumours that were mainly moderately or strongly hyperattenuating (53%). In univariate analysis, poor tumoral differentiation, hepatic metastasis, high mitotic index, poor tumoral enhancement at the pancreatic phase and less vascularised tumours were correlated with decreased survival rate. CONCLUSION: Enhancement of EPT at CT is correlated with tumour vascularity assessed by light microscopy. Low-enhancing EPT at CT are correlated with poorly differentiated EPT and with a decrease in overall survival.

[Intraosseous meningioma of the skull: radiologic pathologic correlation]. / Méningiome intra-osseux de la voûte du crâne: confrontation anatomo-radiologique.

Intraosseous meningiomas are rare ectopic meningiomas. The authors report the case of a hyperostotic intraosseous meningioma of the parietal bone without dural extension. The preoperative imaging findings, as well as imaging features of the surgical specimen and pathologic findings are discussed.

Diffusion-weighted MR imaging and pathologic findings in adult cerebellar medulloblastoma.

UNLABELLED: OBJECTIVES, MATERIALS AND METHODS: The authors present the diffusion-weighted MR imaging and pathologic findings in two adult patients with cerebellar medulloblastoma. RESULTS: Both presented with a vermian mass of the posterior fossa with low signal on SE T1 weighted images, and moderate enhancement of the mass after gadolinium injection. The tumors were of high intensity on diffusion-weighted images with low ADC value. The ADC values (x10(-3) mm2/s) were respectively 0.60 +/- 0.06 and 0.59+/-0.11 (tumor), and 0.65 +/- 0.04 and 0.67 +/- 0.07 (cerebellar white matter). Tumors were highly cellular and composed of densely packed small round cells with hyperchromatic nuclei and scanty cytoplasm. CONCLUSION: diffusion-weighted MR imaging may be useful for the diagnosis of cerebellar medulloblastoma, due to their high cellularity and high nuclear-to-cytoplasmic ratio.

Imaging of MALT lymphomas.

The broad category of non-Hodgkin's lymphoma includes a large variety of different diseases including indolent as well as aggressive lymphomas. Mucosa-associated lymphoid tissue (MALT) lymphoma arises in the extranodal mucosal lymphoid tissue and has only been recognised as a distinct entity in recent years. It affects one or several extranodal structures such as the stomach, the lung, the eye and salivary glands. The lymphoma is generally of low grade and has indolent course. The aim of this article is to exemplify the most common radiological patterns of MALT lymphoma.