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.

[Nonketotic hyperglycemia-induced hemiballism]

Nonketotic hyperglycemia-induced hemichorea or hemiballism is a well-recognized entity that is rarely encountered. Particular computed tomography and magnetic resonance imaging findings have been described. The pathophysiological mechanism of this disease remains uncertain. We report here on two female patients that presented with hemiballism secondary to nonketotic hyperglycemia and underwent brain computed tomography and magnetic resonance imaging.

Feasibility of dynamic MRI for evaluating velopharyngeal insufficiency in children

OBJECTIVE

To demonstrate the feasibility of dynamic MRI with near-real-time temporal resolution for analysing velopharyngeal closure.

METHODS

Eleven children and young adults (seven girls, four boys, mean age: 8.4 years) with suspected velopharyngeal insufficiency (VPI), and one healthy volunteer underwent MRI (1.5 Tesla) using T2 fast imaging sequences. Imaging was done without any sedation at rest and during various phonations in the axial and sagittal planes. Images were analysed by two radiologists, a plastic surgeon and a speech therapist.

RESULTS

The MRI examinations were well tolerated by even the youngest patient. A qualitative analysis found that the sagittal dynamic sequences during phonation were in relation to the clinical data in all patients. A quantitative analysis enabled calculation of the elevation angle of the soft palate in relation to the hard palate, the velar eminence angle and the percentage of reduction of the antero-posterior diameter of the pharyngeal lumen.

CONCLUSION

Dynamic MRI is a non-invasive, rapid and repeatable method. It can be considered a complementary tool to endoscopy and fluoroscopy, particularly in children, for assessing VPI without any sedation or radiation exposure.

[Transarterial embolization of intracranial dural arteriovenous malformations with ethylene vinyl alcohol copolymer (Onyx18): report of three cases]

BACKGROUND

This is a report of the endovascular treatment of three intracranial dural arteriovenous malformations (DAVM) using Onyx.

PATIENTS AND METHODS

We analyzed the clinical and angiographic results in three patients with intracranial DAVM, revealed by a hemorrhagic event and treated by endovascular way by the use Onyx. Angiographic investigation showed the DAVM to be located in the lateral sinus in two cases and in the tentorium region in the third.

RESULTS

In all three cases, embolization was performed by selective catheterization of the meningeal arterial feeder of the DAVM. The injection of Onyx resulted in complete anatomical exclusion of the DAVM, as demonstrated by posttreatment angiography. Clinically, the patients recovered partially or completely their neurological deficit.

CONCLUSION

Onyx is a liquid embolization agent recently introduced for the treatment of DAVM. When used under optimal conditions, it offers a feasible alternative option in the treatment of such vascular malformations.

Intramedullary neurenteric cyst without concurrent malformation

Neurenteric cysts (NECs) are dysraphic lesions. They are usually extramedullary, the intramedullary forms are very rare. To our knowledge, only 10 cases of isolated intramedullary NECs have been reported. We report a case of intramedullary NEC without any associated dysraphic lesion. The clinical findings were: cervical pain and left hemicorporal weakness which predominated at the upper limb. Neuroradiological evaluation was performed by means of MRI which revealed a cystic lesion at C3-C4 level. A partial excision was performed and the diagnosis of NEC was established by histological study.

Atypical CT and MRI aspects of an epidermoid cyst

We report a case of an unusual epidermoid cyst (EC) of the cerebellopontine angle that appeared hyperdense on computed tomography (CT) scanning, hyperintense on T1-weighted MR images and hypointense on T2-weighted magnetic resonance (MR) images. Diffusion-weighted imaging showed a hypointense lesion. We discuss imaging characteristics of ECs, explain the atypical findings in our case and confirm that the signal seen on diffusion-weighted images in the EC is related to a T2 effect.

Reversible metronidazole-induced encephalopathy

We report the neuroimaging findings of a case of reversible metronidazole-induced encephalopathy. Magnetic resonance imaging (MRI) demonstrated lesions in highly suggestive locations. Follow-up imaging performed 1 month after cessation of metronidazole therapy demonstrated resolution of imaging findings.