Spontaneous shrinkage of sporadic vestibular schwannomas: a clinical and radiological analysis

OBJECTIVE

The natural history of sporadic vestibular schwannoma (VS) is unpredictable, as tumors may or may not grow and can even spontaneously regress. A spontaneous VS shrinkage MRI-based pattern has been proposed with either a scalloped tumor aspect in the cerebellopontine angle or the appearance of a CSF-filled space surrounding the intracanalicular (IC) tumor within an enlarged canal. The authors of this retrospective study aimed to describe the evolution of sporadic VSs with radiological signs of VS regression and to identify prognostic factors for tumor shrinkage.

METHODS

All MRI scans obtained during patient follow-up were reviewed for extracanalicular (EC) and IC size and tumor characteristics. Volumetric measurements were performed on the first and last MRI scans. Shrinkage was considered to have occurred if the tumor size had decreased by ≥ 2 mm in its largest diameter and/or if the volume had decreased by ≥ 20%. Audiometric data were also collected.

RESULTS

Among 512 patients under observation for sporadic VSs, 66 (13%) had at least one radiological sign of VS regression and 31 of these (6% overall) had confirmed tumor shrinkage. The mean follow-up was 4 ± 2.5 years. One radiological sign was present on initial MRI in 58% of patients and appeared during the follow-up period in the remaining 42%. Two groups were identified: 31 patients (47%) demonstrated progressive tumor regression during follow-up, and tumors in 35 patients (53%) remained stable once signs of regression were identified (assuming a stabilized regression). The prognostic factors for VS regression were as follows: EC VS extension (p = 0.02), cystic lesion (p = 0.002), and central necrosis (p = 0.02). The mean pure-tone average (PTA) was 43 ± 26.2 dB at the time of diagnosis and 53 ± 28.3 dB at the last visit (p < 0.0001). Among patients with an observed tumor shrinkage, ∆PTA was lower if the inner ear signal on the high-resolution T2-weighted image had improved (-3 ± 8.9 dB, n = 11) than if the inner ear signal had not improved (-10 ± 6.9 dB, n = 20) (p = 0.02) between the initial and last MRI scans.

CONCLUSIONS

Spontaneous shrinkage of sporadic VSs could be suspected based on two radiological aspects that are indicative of VSs in progressive or stabilized regression and is an additional argument for the conservative management of these tumors. During follow-up, recovery from a reduced to a normal cochlear fluid MRI signal is a good indicator for hearing preservation.

"National survey for preliminary evaluation of neuroradiological protocols in patients with infective endocarditis"

OBJECTIVES

The aim of this study was to identify imaging protocols in patients with infective endocarditis through a nationwide survey.

METHODS

An electronic evolutionary survey was sent to interventional Neuroradiologists among neuroradiological centers, under the aegis of the Société Française de Neuroradiologie. Among 33 contacted centers, 25 completed the survey (21 universitary hospitals and 4 peripheric hospitals).

RESULTS

Most of the centers (88%) used systematic imaging screening in IE patients. MRI was the first imaging method used in 66% of cases, while CT was used in 44%. When no IIA was detectable in CT-scan screening, 6 (54,54%) stopped investigations, while 9 (81,81%) continued with MRI exploration in case of hemorrhage, ischemia or enhancement. Sulcal hemorrhage on MRI was an indication of complementary DSA in 25 centers (100%). Regarding IIA characterization, 12 centers (48%) used systematic DSA, whereas for 10 centers (40%), DSA was conditioned by hemorrhage or patient status.

CONCLUSION

We highlighted large variations in Neuroimaging exploration and follow-up of IE patients in real-world practices. Expert guidelines able to standardize practices are warranted to improve the management of this serious and often misdiagnosed pathology.

Brain Glucose Metabolism in Cerebral Amyloid Angiopathy: An FDG-PET Study

BACKGROUND AND PURPOSE

The in vivo diagnosis of cerebral amyloid angiopathy (CAA) is currently based on the Boston criteria, which largely rely on hemorrhagic features on brain magnetic resonance imaging. Adding to these criteria ¹⁸F-fluoro-deoxy-D-glucose (FDG) positron emission tomography, a widely available imaging modality, might improve their accuracy. Here we tested the hypothesis that FDG uptake is reduced in posterior cortical areas, particularly the primary occipital cortex, which pathologically bear the brunt of vascular Aβ deposition.

METHODS

From a large memory clinic database, we retrospectively included all patients in whom both brain magnetic resonance imaging and FDG positron emission tomography had been obtained as part of routine clinical care and who fulfilled the Boston criteria for probable CAA. None had a history of symptomatic intracerebral hemorrhage. FDG data processing involved (1) spatial normalization to the Montreal Neurology Institute/International Consortium for Brain Mapping 152 space and (2) generation of standardized FDG uptake (relative standardized uptake value; relative to the pons). The relative standardized uptake value data obtained in 13 regions of interest sampling key cortical areas and the cerebellum were compared between the CAA and age-matched control groups using 2 separate healthy subject databases and image-processing pipelines. The presence of significant hypometabolism (2-tailed P<0.05) was assessed for the bilaterally averaged regions-of-interest relative standardized uptake values.

RESULTS

Fourteen patients fulfilling the Boston criteria for probable CAA (≥2 exclusively lobar microbleeds) were identified. Significant hypometabolism (P range, 0.047 to <0.0001) consistently affected the posterior cortical areas, including the superior and inferior parietal, primary visual, lateral occipital, lateral temporal, precuneus, and posterior cingulate regions of interest. The anterior cortical areas were marginally or not significantly hypometabolic, and the cerebellum was spared.

CONCLUSIONS

Supporting our hypothesis, significant glucose hypometabolism predominantly affected posterior cortical regions, including the visual cortex. These findings from a small sample may have diagnostic implications but require replication in larger prospective studies. In addition, whether they generalize to CAA-related symptomatic intracerebral hemorrhage warrants specific studies.

[18 F]FDG PET may differentiate cerebral amyloid angiopathy from Alzheimer's disease

BACKGROUND

Cerebral amyloid angiopathy (CAA) is a frequent cause of both intracerebral hemorrhage (ICH) and cognitive impairment in the elderly. Diagnosis relies on the Boston criteria, which use magnetic resonance imaging markers including ≥2 exclusively lobar cerebral microbleeds (lCMBs). Although amyloid positron emission tomography (PET) may provide molecular diagnosis, its specificity relative to Alzheimer's disease (AD) is limited due to the prevalence of positive amyloid PET in cognitively normal elderly. Using early-phase ¹¹ C-Pittsburgh compound B as surrogate for tissue perfusion, a significantly lower occipital/posterior cingulate (O/PC) tracer uptake ratio in probable CAA relative to AD was recently reported, consistent with histopathological lesion distribution. We tested whether this finding could be reproduced using [¹⁸ F]fluorodeoxyglucose (FDG)-PET, a widely available modality that correlates well with early-phase amyloid PET in both healthy subjects and AD.

METHODS

From a large memory clinic database, we retrospectively included 14 patients with probable CAA (Boston criteria) and 21 patients with no lCMB fulfilling AD criteria including cerebrospinal fluid biomarkers. In all, [¹⁸ F]FDG-PET/computed tomography (CT) was available as part of routine care. No subject had a clinical history of ICH. Regional standardized [¹⁸ F]FDG uptake values normalized to the pons (standard uptake value ratio [SUVr]) were obtained, and the O/PC ratio was calculated.

RESULTS

The SUVr O/PC ratio was significantly lower in CAA versus AD (1.02 ± 0.14 vs. 1.19 ± 0.18, respectively; p = 0.024).

CONCLUSIONS

Despite the small sample, our findings are consistent with the previous early-phase amyloid PET study. Thus, [¹⁸ F]FDG-PET may help differentiate CAA from AD, particularly in cases of amyloid PET positivity. Larger prospective studies, including in CAA-related ICH, are however warranted.

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.

How to radiologically identify a spontaneous regression of sporadic vestibular schwannoma?

Background

The natural history of sporadic vestibular schwannoma is unpredictable, with tumors growing, non-growing and even showing spontaneous regression in some rare cases.

Objective

This retrospective study aims to describe the radiologic signs characterizing and identifying the shrinking vestibular schwannoma.

Methods

Involution was considered to have occurred if tumor size had decreased by 2 mm or more on its largest diameter. All magnetic resonance imaging scans were reviewed for tumor size, internal auditory meatus size, and tumor characteristics. Volumetric measurements were performed on the first and last scan. Audiometric data were collected at the first and last visit.

Results

Fourteen patients with a confirmed spontaneous regression were included, with a mean follow-up of 5 ± 2.6 years. The mean shrinkage rate was 0.9 ± 0.59 mm/year on 2D measurements, and 0.2 ± 0.17 cm³/year on volumetric measurements, with a relative shrinkage of 40 ± 16.9%. Two remarkable radiologic features were observed: First, a festooned aspect, defined by multiple curves in the tumor outline, noticed in 12 cases (86%); second, the appearance of cerebrospinal fluid filling the internal auditory meatus, associated with an enlargement of the internal auditory meatus compared to the contralateral side, and observed in 10 out of 13 cases with internal auditory meatus invasion (77%). Those two aspects were associated in 64% of cases.

Conclusion

These two newly reported radiologic features could help neurosurgeons, oto-neurosurgeons and neuroradiologists to identify a spontaneous vestibular schwannoma involution at first visit. This could allow any treatment to be postponed, monitoring to be more widely spaced, and patients to be reassured.

Pulse-triggered DTI sequence with reduced FOV and coronal acquisition at 3T for the assessment of the cervical spinal cord in patients with myelitis

BACKGROUND AND PURPOSE

DTI is a promising technique for imaging of the spinal cord, but the technique has susceptibility-induced artifacts. We evaluated a pulse-triggered DTI sequence with an rFOV technique and coronal acquisition for the assessment of the cervical spinal cord in patients with myelitis at 3T.

MATERIALS AND METHODS

A rFOV acquisition was established by a noncoplanar application of the excitation and the refocusing pulse in conjunction with outer volume suppression. The DTI sequence was performed in the coronal plane in 12 healthy volunteers and 40 consecutive patients with myelitis. Probabilistic tractography of the posterior and lateral funiculi was performed from the C1 to C7 levels. FA, MD, aD, rD, and ratios of aD and rD were measured.

RESULTS

In healthy volunteers, mean DTI indices within the whole-fiber pathways were the following: FA = 0.61, MD = 1.17 × 10(-3) mm(2)/s, aD = 1.96 × 10(-3) mm(2)/s, rD = 0.77 × 10(-3) mm(2)/s, and ratios of aD and rD = 2.5. Comparison of healthy controls and patients with myelitis identified statistically significant differences for all DTI parameters. Different patterns of myelitis, including spinal cord atrophy and active inflammatory lesions, were recognized. There was a significant correlation between clinical severity and DTI parameters.

CONCLUSIONS

The present work introduces a new approach for DTI of the cervical spinal cord at 3T, enabling a quantitative follow-up of patients with myelitis.

[Susceptibility weighted magnetic resonance sequences "SWAN, SWI and VenoBOLD": technical aspects and clinical applications]

Susceptibility-weighted MR sequences, T2 star weighted angiography (SWAN, General Electric), Susceptibility weighted imaging (SWI, Siemens) and venous blood oxygen level dependant (VenoBOLD, Philips) are 3D spoiled gradient-echo sequence that provide a high sensitivity for the detection of blood degradation products, calcifications, and iron deposits. For all these sequences, an appropriate echo time allows for the visualization of susceptibility differences between adjacent tissues. However, each of these sequences presents a specific technical background. The purpose of this review was to describe 1/the technical aspects of SWAN, VenoBOLD and SWI sequences, 2/the differences observed in term of contrast within the images, 3/the key imaging findings in neuroimaging using susceptibility-weighted MR sequences.

Optimization of bacterial diagnosis yield after needle aspiration in immunocompetent adults with brain abscesses

OBJECTIVE

Brain abscesses (BA) are life threatening, even in immunocompetent patients, in part because microbiological diagnosis is often lacking and management is empirical. Recent epidemiological changes make it all the more important to have a precise microbiological diagnosis. Our purpose was to evaluate the efficacy of a strategy aimed at obtaining a microbiological diagnosis in immunocompetent patients presenting with suspected BAs.

METHODS

We conducted a cohort study including all consecutive patients suspected of having BAs according to clinical, biological, and radiological findings. Severely immunocompromised patients were excluded. Aspiration was performed free-hand in patients with superficial abscesses (<1 cm depth from the cortical surface) and under stereotactic guidance in patients with deep-seated abscesses. Microbiological diagnosis was optimized, using the best aerobic and anaerobic growth conditions, blood culture bottles inoculated in the operating room, and molecular biology techniques if necessary. Antibiotic treatment was adapted according to the findings.

RESULTS

Twenty-six patients were suspected of having BAs during the study period. Twenty-four patients benefited from aspiration (stereotactic puncture in 3 cases), which was safe, confirmed the diagnosis of BAs, and yielded microbiological diagnosis in all cases, even in those patients who had previously received antibiotics (n = 8; 33%). In 10 patients (42%), microbiological results led to a different choice in antibiotic therapy than the recommended empirical regimen.

CONCLUSION

Microbiological diagnosis can be obtained in all cases of BA. This is achieved by the conjunction of rapid needle aspiration and the optimization of microbiological diagnosis resulting from fast management of the surgical specimen, good anaerobic culture conditions, and the use of blood culture bottles and molecular biology techniques when appropriate. Moreover, it is of clinical and therapeutic interest when BAs are suspected in immunocompetent patients.

Ostéomyélite de la base du crâne d'origine otosinusienne. Étude d'une série de cinq cas récents

INTRODUCTION

Skull base osteomyelitis is an uncommon but severe condition generally secondary to necrotizing otitis externa. The aim of this study was to determine the patients demographics, clinical and radiological findings, and outcomes of this condition.

MATERIAL AND METHODS

We prospectively follow 5 patients with a diagnosis of skull base osteomyelitis between 2004 and 2005. Clinical, biologic and imaging data were collected, and also follow-up during treatment.

RESULTS

The five patients were men and the average age at presentation was 75 years (63-89). All except one had a previous diabetes mellitus, with a more or less recent clinical story of otitis externa. All of them suffered of headaches and cranial nerve(s) deficits, particularly facial nerve. Diagnosis was made on MRI with gadolinium injection and fat saturation, and Pseudomonas aeruginosa identified as pathogen in all cases. One patient deceased of cranial nerves palsy complication. In 4 cases we found previously a too short or non adapted treatment of necrotizing otitis externa.

CONCLUSIONS

In the setting of headache, cranial nerves deficit and abnormal skull base imaging on MRI with Fat sat, osteomyelitis should be consider as the likely diagnosis. This complication should be avoided by optimal management of necrotizing otitis externa.

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.

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

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.

Helical CT of pancreatic endocrine tumors

Pancreatic endocrine tumors are rare neoplasms. It is important to distinguish them from the more common ductal adenocarcinoma of the pancreas because they are slowly progressive and specific treatments are available. The CT findings of pancreatic endocrine tumors usually vary according to the functioning or nonfunctioning status. In this article, the authors illustrate typical and atypical CT findings of pancreatic endocrine tumors with radiopathologic correlations and give examples of other pancreatic conditions mimicking pancreatic endocrine tumors.

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.