Spontaneous modifications of contrast enhancement in childhood non-cerebellar pilocytic astrocytomas

Comparison of volumetric and 2D-based response methods in the PNOC-001 pediatric low-grade glioma clinical trial

Background

Although response in pediatric low-grade glioma (pLGG) includes volumetric assessment, more simplified 2D-based methods are often used in clinical trials. The study's purpose was to compare volumetric to 2D methods.

Methods

An expert neuroradiologist performed solid and whole tumor (including cyst and edema) volumetric measurements on MR images using a PACS-based manual segmentation tool in 43 pLGG participants (213 total follow-up images) from the Pacific Pediatric Neuro-Oncology Consortium (PNOC-001) trial. Classification based on changes in volumetric and 2D measurements of solid tumor were compared to neuroradiologist visual response assessment using the Brain Tumor Reporting and Data System (BT-RADS) criteria for a subset of 65 images using receiver operating characteristic (ROC) analysis. Longitudinal modeling of solid tumor volume was used to predict BT-RADS classification in 54 of the 65 images.

Results

There was a significant difference in ROC area under the curve between 3D solid tumor volume and 2D area (0.96 vs 0.78, P = .005) and between 3D solid and 3D whole volume (0.96 vs 0.84, P = .006) when classifying BT-RADS progressive disease (PD). Thresholds of 15-25% increase in 3D solid tumor volume had an 80% sensitivity in classifying BT-RADS PD included in their 95% confidence intervals. The longitudinal model of solid volume response had a sensitivity of 82% and a positive predictive value of 67% for detecting BT-RADS PD.

Conclusions

Volumetric analysis of solid tumor was significantly better than 2D measurements in classifying tumor progression as determined by BT-RADS criteria and will enable more comprehensive clinical management.

Tumor load rather than contrast enhancement is associated with the visual function of children and adolescents with optic pathway glioma - a retrospective Magnetic Resonance Imaging study

Introduction

Optic pathway gliomas are often asymptomatic tumors occurring in children with neurofibromatosis type 1 (NF1 + OPG) or sporadically (spOPG). Treatment is usually prompted by visual loss and/or tumor progression on MRI. The aim of this study was to investigate the relationship between visual acuity (VA), tumor growth, and contrast enhancement to provide more distinct indications for the administration of gadolinium-based contrast agents.

Methods

Tumor load was retrospectively measured and enhancement semi-quantitatively scored on 298 MRIs of 35 patients (63% NF1 + OPG). Spearman rank correlation between tumor load and enhancement was calculated and a linear mixed model used to examine the influence of tumor load and enhancement on corresponding VA tests (LogMAR).

Results

The optic nerve width in NF1 + OPGs was strongly associated with VA (regression coefficient 0.75; confidence interval 0.61—0.88), but weakly with enhancement (0.06; −0.04—0.15). In spOPGs, tumor volume and optic nerve width were more relevant (0.31; −0.19—0.81 and 0.39; 0.05—0.73) than enhancement (0.09; −0.09—0.27).

Conclusions

Tumor load measures may be more relevant for the surveillance of optic pathway gliomas than enhancement, given that VA is the relevant outcome parameter. Regular contrast administration should therefore be questioned in these patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11060-021-03941-1.

Pseudoprogression is frequent following front-line radiotherapy in pediatric low-grade glioma - results from the German LGG cohort

PURPOSE

Expansion of MRI T2- and/or T1-tumor lesion volume after radiotherapy (RT) may indicate pseudoprogression (PsPD). The differentiation between true progression and PsPD is a clinical challenge and under-investigated in pediatric low-grade glioma (LGG). We evaluated radiological criteria for PsPD following front-line RT and investigated the frequency and duration of PsPD following three RT-modalities within the framework of the [Anonymized for Review] LGG-studies.

METHODS

Baseline and follow-up MRI-scans of 136 patients (72 [52.9%] male, median age at start of RT 11.3 years [range 0.8-25.9]) of the [Anonymized for Review] cohorts (¹²⁵iodine-interstitial RT [IS; n=51], photon-beam [XRT; n=60] or proton-beam RT [PBT; n=25]) were centrally evaluated for: Increasing 1) total tumor-associated T2-lesion, 2) focal tumor-associated T2-lesion and 3) contrast-enhancing tumor over a period of 24 months following RT. The pattern of these criteria initiated "suspicion" of PsPD, their evolution determined "definite" PsPD.

RESULTS

Definite PsPD was radiologically determined in 54/136 (39.7%) without differences in frequency between RT-modalities: IS 22/48 vs. XRT 24/54 vs. PBT 11/20; p=0.780. Definite PsPD occurred at median 6.3 months (IS 7.2 months; XRT 4.4 months; PBT 6.5 months) after RT-initiation and persisted for median 7.2 months (IS 8.5 months; XRT 7 months; PBT 7.4 months). Appearance of necrosis within the focal tumor-associated T2-lesion proved to be a relevant associated predictor of definite PsPD (p<0.001).

CONCLUSIONS

PsPD is frequent following irradiation of pediatric LGG and independent of the RT-modality (IS vs. XRT vs. PBT). Adequate identification of PsPD versus true progression is imperative to prevent unneeded salvage treatment.

The rosette-forming glioneuronal tumor mimicked cerebral cysticercosis: a case report

INTRODUCTION

Rosette-forming glioneuronal tumor (RGNT) is a rare variety of slow growing mixed glioneuronal tumor involving primarily fourth ventricular region. This is a comprehensive analysis of a 22-year-old woman with RGNT composed of mainly cystic components. In addition, the case showed multiple lesions located in brain parenchyma which mimicked cerebral cysticercosis. Here, we analyzed this case and listed some characteristics of RGNTs in reported literature which occurring in atypical locations for further understanding it.

CASE REPORT

A 22-year-old woman presented with a history of transient dizziness, nausea, and vomiting. Magnetic resonance imaging (MRI) showed multiple cystic lesions in brain parenchyma and then the patient was diagnosed with cerebral cysticercosis possibility. Empirical anti-infective therapy in addition to a follow-up post 2 weeks of MRI examination showed the lesions unchanged. Finally, a biopsy of the right cerebellar hemisphere lesions verified RGNT.

CONCLUSION

RGNT is an uncommon tumor classified as grade I glioma by World Health Organization (WHO) with slightly longer course. The imaging findings of RGNT are not specific especially in atypical areas. RGNT is rare, but we should also consider the possibility in diagnosis and differential diagnosis.

Current status and recommendations for imaging in neurofibromatosis type 1, neurofibromatosis type 2, and schwannomatosis

Neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis (SWN) are three clinically distinct tumor predisposition syndromes with a shared tendency to develop peripheral and central nervous system neoplasms. Disease expression and complications of NF1, NF2, and SWN are highly variable, necessitating a multidisciplinary approach to care in order to optimize outcomes. This review will discuss the imaging appearance of NF1, NF2, and SWN and highlight the important role that imaging plays in informing management decisions in people with tumors associated with these syndromes. Recent technological advances, including the role of both whole-body and localized imaging strategies, routine anatomic and advanced magnetic resonance (MR) imaging sequences such as diffusion-weighted imaging (DWI) with quantitative apparent diffusion coefficient (ADC) mapping, and metabolic imaging techniques (MR spectroscopy and positron emission testing) are discussed in the context of the diagnosis and management of people with NF1, NF2, and SWN based on the most up-to-date clinical imaging studies.

Risk of Optic Pathway Glioma in Neurofibromatosis Type 1: No Evidence of Genotype-Phenotype Correlations in A Large Independent Cohort

The occurrence of optic pathway gliomas (OPGs) in children with neurofibromatosis type 1 (NF1) still raises many questions regarding screening and surveillance because of the lack of robust prognostic factors. Recent studies of an overall cohort of 381 patients have suggested that the genotype may be the main determinant of the development of OPG, with the risk being higher in patients harbouring NF1 mutations in the 5' tertile and the cysteine/serine-rich domain. In an attempt to confirm this hypothesis, we used strict criteria to select a large independent cohort of 309 NF1 patients with defined constitutional NF1 mutations and appropriate brain images (255 directly enrolled and 54 as a result of a literature search). One hundred and thirty-two patients had OPG and 177 did not. The association of the position (tertiles and functional domains) and type of NF1 mutation with the development of OPG was analysed using the χ2 test and Fisher's exact probability test; odds ratios (ORs) with 95% confidence intervals were calculated, and Bonferroni's correction for multiple comparisons was applied; multiple logistic regression was also used to study genotype-phenotype associations further. Our findings show no significant correlation between the site/type of NF1 mutation and the risk of OPG, and thus do not support the hypothesis that certain constitutional mutations provide prognostic information in this regard. In addition, we combined our cohort with a previously described cohort of 381 patients for a total of 690 patients and statistically re-analysed the results. The re-analysis confirmed that there were no correlations between the site (tertile and domain) and the risk of OPG, thus further strengthening our conclusions.

A case of a rosette-forming glioneuronal tumor arising from the pons with disappearance of contrast enhancement

A rosette-forming glioneuronal tumor (RGNT) is a rare and slow-growing central nervous system tumor. This tumor is usually assessed by MRI during the follow-up period. RGNT can show alteration of contrast enhancement regardless of tumor growth. Here, we report a case of RGNT arising from pons which shows partial enhancement on initial MRI, smaller enhancement on follow-up MRI at 10 months, and totally disappeared at 18 months without any therapy.

Pontine tumor in a neonate: case report and analysis of the current literature

Tumors of the central nervous system represent the largest group of solid tumors found in pediatric patients. Pilocytic astrocytoma is the most common pediatric glioma, mostly located in the posterior fossa. The majority of brainstem tumors, however, are classified as highly aggressive diffuse intrinsic pontine gliomas (DIPGs) and their prognosis is dismal.The authors report on the case of a neonate in whom MRI and neuropathological assessment were used to diagnose DIPG. Before initiation of the planned chemotherapy, the tumor regressed spontaneously, and the newborn exhibited a normal neurological development. Meanwhile, Illumina Human Methylation450 BeadChip analysis reclassified the tumor as pilocytic astrocytoma of the posterior fossa.In conclusion, the authors advocate not initiating immediate intensive therapy in newborns with brain tumors, even with classical appearance of a DIPG; rather, they would like to encourage a biopsy to define the best individual therapeutic approach and avoid ineffective chemotherapy.

Detection of recurrent brain tumors in children: No significant difference in sensitivity between unenhanced and contrast-enhanced MRI

BACKGROUND

Magnetic resonance imaging (MRI) with a gadolinium injection is currently used in the follow-up of children in remission of cerebral tumors (CTs). Intracerebral gadolinium deposition has been recently reported with unknown risks. The aim of this study was to evaluate the sensitivity of unenhanced brain MRI (U-MRI) in detection of tumor recurrence.

METHODS AND MATERIALS

A set of 58 U-MRIs of children in remission was retrospectively evaluated by three seniors (a neuroradiologist, a pediatric and a general radiologist) and one junior to look for any recurrence. Clinical, tumoral and imaging data were collected. The final diagnosis was anatomopathological when available, or the clinicoradiological evolution. Sensitivity, specificity, predictive values and interobserver agreement were calculated. A Fisher test and Fleiss kappa coefficient were performed.

RESULTS

For the seniors, the U-MRI had a sensitivity of 81% (95% confidence interval (CI): 0.56-0.90), and a negative predictive value (NPV) of 82% (95% CI: 0.63-0.94). The U-MRI sensitivity, regardless of the observer, was not significantly different from the contrast-enhanced MRI sensitivity (86%) according to a Fisher test (p > 0.05). No significant difference in sensitivity within the subgroups was found. The interobserver agreement of seniors was good (κ = 0.68).

CONCLUSION

U-MRI brain was suboptimal for 80% of patients. Three-dimensional millimetric, fluid-attenuated inversion recovery, and diffusion would constitute helpful sequences in follow-up. Further specific studies depending on each tumor type are still required to determine whether a potential abstention of gadolinium intravenous injection should be discussed for children.

Current concepts in radiologic assessment of pediatric brain tumors during treatment, part 1

Pediatric brain tumors differ from those in adults by location, phenotype and genotype. In addition, they show dissimilar imaging characteristics before and after treatment. While adult brain tumor treatment effects are primarily assessed on MRI by measuring the contrast-enhancing components in addition to abnormalities on T2-weighted and fluid-attenuated inversion recovery images, these methods cannot be simply extrapolated to pediatric central nervous system tumors. A number of researchers have attempted to solve the problem of tumor assessment during treatment in pediatric neuro-oncology; specifically, the Response Assessment in Pediatric Neuro-Oncology (RAPNO) working group was recently established to deal with the distinct challenges in evaluating treatment-related changes on imaging, but no established criteria are available. In this article we review the current methods to evaluate brain tumor therapy and the numerous challenges that remain. In part 1, we examine the role of T2-weighted imaging and fluid-attenuated inversion recovery sequences, contrast enhancement, volumetrics and diffusion imaging techniques. We pay particular attention to several specific pediatric brain tumors, such as optic pathway glioma, diffuse midline glioma and medulloblastoma. Finally, we review the best means to assess leptomeningeal seeding.

Surveillance magnetic resonance imaging for isolated optic pathway gliomas: is gadolinium necessary?

BACKGROUND

Pediatric optic pathway gliomas are typically indolent but have a variable clinical course. Treatment is dictated by symptoms and changes on contrast-enhanced MRI examinations. Gadolinium retention in children has motivated parsimonious use of gadolinium-based contrast agents.

OBJECTIVES

To determine surveillance MR factors that motivate changes in tumor-directed therapies and extrapolate cost-efficacy of a non-contrast follow-up protocol.

MATERIALS AND METHODS

Using an imaging database search we identified children with isolated optic pathway gliomas and ≥3 follow-up contrast-enhanced MRIs. We reviewed medical records and imaging for: (1) coincident changes on contrast-enhanced MRI and tumor-directed therapy, (2) demographics and duration of follow-up, (3) motivations for intervention, (4) assessment of gadolinium-based contrast agents' utility and (5) health care utilization data. We assessed cost impact in terms of relative value unit (RVU) burden.

RESULTS

We included 17 neurofibromatosis type 1 (NF1) and 21 non-NF1 patients who underwent a median 16.9 and 24.3 cumulative contrast-enhanced MR exams over 7.7 years and 8.1 years of follow-up, respectively. Eight children (one with NF1) had intervention based on contrast-enhanced MR findings alone. For these eight, increased tumor size was the only common feature, and it was apparent on non-contrast T2 sequences. For the median patient, a non-contrast follow-up protocol could result in 15.9 (NF1) and 23.3 (non-NF1) fewer gadolinium-based contrast agent administrations, and a 39% lower yearly RVU burden.

CONCLUSION

Pediatric patients with isolated optic pathway gliomas undergo a large number of routine contrast-enhanced MR follow-up exams. Gadolinium might not be needed for these exams to inform management decisions. Secondary benefits of a non-contrast follow-up protocol include decreased cost and risk to the patient.

Optic Pathway Gliomas in Neurofibromatosis Type 1: An Update: Surveillance, Treatment Indications, and Biomarkers of Vision

Optic pathway gliomas (OPGs) occur in 15%-20% of children with neurofibromatosis type 1 (NF1), leading to visual deficits in fewer than half of these individuals. The goal of chemotherapy is to preserve vision, but vision loss in NF1-associated OPG can be unpredictable. Determining which child would benefit from chemotherapy and, equally important, which child is better observed without treatment can be difficult. Unfortunately, despite frequent imaging and ophthalmologic evaluations, some children experience progressive vision loss before treatment. Indications for chemotherapy usually are based on a comprehensive, quantitative assessment of vision, but reliable vision evaluation can be challenging in young children with NF1-OPG. The ability to identify and predict impending vision loss could potentially improve management decisions and visual outcomes. To address this challenge, ophthalmologic, electrophysiologic, and imaging biomarkers of vision in NF1-OPG have been proposed. We review current recommendations for the surveillance of children at risk for NF1-OPG, outline guidelines for initiating therapy, and describe the utility of proposed biomarkers for vision.

MR imaging of brain pilocytic astrocytoma: beyond the stereotype of benign astrocytoma

BACKGROUND

Pilocytic astrocytoma (PA) is the most common pediatric brain glioma and is considered the prototype of benign circumscribed astrocytoma. Despite its low malignancy, the CT and MRI features of brain PA may resemble those of much more aggressive brain tumors. Misdiagnosis of PA is particularly easy when it demonstrates MR morphological and non-morphological findings that are inconsistent with its non-aggressive nature and that overlap with the features of more aggressive brain tumors.

METHOD

Basing on the evidence that the variation in the histological, genetic, and metabolic "fingerprint" for brain PA is dependent on tumor location, and the hypothesis that tumor location is related to the broad spectrum of morphological and non-morphological MR imaging findings, the authors discuss the MR imaging appearance of brain PA using a location-based approach to underline the typical and less typical imaging features and the main differential diagnosis of brain PA. A brief summary of the main pathological and clinical features, the natural history, and the treatment of brain PA is also provided.

RESULT

A combination of morphological and non-morphological MR imaging features and a site-based approach to differential diagnosis are required for a pre-operative diagnosis. The new "cutting-edge" MR imaging sequences have the potential to impact the ease and confidence of pediatric brain tumor interpretation and offer a more efficient diagnostic work-up.

CONCLUSIONS

Although the typical imaging features of brain pilocytic astrocytoma make radiological diagnosis relatively easy, an atypical and more aggressive appearance can lead to misdiagnosis. Knowing the broad spectrum of imaging characteristics on conventional and advanced MR imaging is important for accurate pre-operative radiological diagnosis and correctly interpreting changes during follow-up.

Nonrandomized comparison of neurofibromatosis type 1 and non-neurofibromatosis type 1 children who received carboplatin and vincristine for progressive low-grade glioma: A report from the Children's Oncology Group

BACKGROUND

To evaluate tumor responses, event-free survival (EFS), overall survival (OS), and toxicity of chemotherapy, children with neurofibromatosis type 1 (NF1) and progressive low-grade glioma were enrolled into the Children's Oncology Group (COG) A9952 protocol and treated with carboplatin and vincristine (CV).

METHODS

Non-NF1 patients were randomized to CV or thioguanine, procarbazine, 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea, and vincristine in COG A9952. NF1 patients were assigned to CV only. NF1 patients and non-NF1 patients who were treated with CV were compared with respect to baseline characteristics, toxicity, tumor responses, EFS, and OS.

RESULTS

A total of 127 eligible patients with NF1 were nonrandomly assigned to CV: 42 NF1 patients (33%) had events, and 6 (4.7%) died. The 5-year EFS rate was 69% ± 4% for the CV-NF1 group and 39% ± 4% for the CV-non-NF1 group (P < .001). In a univariate analysis, NF1 children had a significantly higher tumor response rate and superior EFS and OS in comparison with CV-treated children without NF1. NF1 patients and non-NF1 patients differed significantly in amount of residual tumor, extent of resection, tumor location, and pathology. According to a multivariate analysis, NF1 was independently associated with better EFS (P < .001) but not with OS. NF1 patients also had a decreased risk of grade 3 or 4 toxicities in comparison with non-NF1 patients. Three second malignant neoplasms occurred in NF1 patients receiving CV (CV-NF1 group) at a median of 7.8 years (range, 7.3-9.4 years) after enrollment, but there were none in the non-NF1 group.

CONCLUSIONS

Children with NF1 tolerated CV well and had tumor response rates and EFS that were superior to those for children without NF1. Cancer 2016;122:1928-36. © 2016 American Cancer Society.

Rosette-forming Glioneuronal Tumor: Rare Case Presented with Spontaneous Disappearance of Contrast Enhancement

This report presents rosette-forming glioneuronal tumor (RGNT) of the tectum in a 24-year-old woman in whom spontaneous disappearance of contrast enhancement (CE) on magnetic resonance (MR) imaging was observed during 9-year follow-up period before therapeutic intervention. MR imaging obtained 9 years ago when she first visited local hospital with headaches showed a mass of the brain stem with CE. Follow-up MR imaging showed disappearance of CE without tumor growth. Nine years later, she was admitted to our hospital with headache and nausea, due to obstructive hydrocephalus. She underwent endoscopic third ventriculostomy (ETV) and tumor biopsy. Histological study revealed RGNT. To our knowledge, this is the first report presenting that the RGNT may show spontaneous disappearance of CE without tumor growth. It is unclear what this phenomenon means, however, knowledge of this phenomenon may be helpful for correct diagnosis and for follow up of RGNT.

Congenital cystic eye associated with a low-grade cerebellar lesion that spontaneously regressed

Background

Congenital cystic eye is an exceedingly rare ocular malformative disease, originated from the failure in the invagination of the optic vesicle during the fetal period and it can be associated with other ocular and non-ocular abnormalities. Diagnosis is based on clinical, radiological and histological features.

Case presentation

We report a case of a congenital cystic eye associated with a cerebellar lesion accidentally detected at magnetic resonance imaging. Biopsy of the mass has not been performed due to parental rejection. Based on radiologic features and absence of clinical signs, a low-grade glioma diagnosis was hypothesized, but histological characterization was not obtained. Follow-up neuro-imaging 6 months after diagnosis showed that intracranial lesion spontaneously regressed without any treatment.

Conclusion

Our report stresses the importance of early MRI in children with ocular malformations, in order to detect associated intracranial defects, also of non-malformative origin. Additionally, we debate the clinic-radiological features of the intracranial lesions that could allow a wait-and-see policy. We also recommend a strict clinical and neuro-imaging follow-up for these lesions. Finally, biological mechanisms at the base of spontaneous regression of the brain lesions are discussed.

Challenges with defining response to antitumor agents in pediatric neuro-oncology: a report from the response assessment in pediatric neuro-oncology (RAPNO) working group

Criteria for new drug approval include demonstration of efficacy. In neuro-oncology, this is determined radiographically utilizing tumor measurements on MRI scans. Limitations of this method have been identified where drug activity is not reflected in decreased tumor size. The RANO (Response Assessment in Neuro-Oncology) working group was established to address limitations in defining endpoints for clinical trials in adult neuro-oncology and to develop standardized response criteria. RAPNO was subsequently established to address unique issues in pediatric neuro-oncology. The aim of this paper is to delineate response criteria issues in pediatric clinical trials as a basis for subsequent recommendations.

Evaluation of the sellar and parasellar regions

The article reviews the anatomy and imaging evaluation of the sellar and parasellar regions. Both common and uncommon sellar and suprasellar masses are reviewed, focusing on a systematic approach to analysis and when appropriate, differential creation.