Cerebellar Mutism Syndrome and Dentato-Thalamo-Cortical Tract Disruption in Diffusion Tractography Following Surgery for Medulloblastoma.

Background Cerebellar mutism syndrome (CMS), a complication following medulloblastoma surgery, has been linked to dentato-thalamo-cortical tract (DTCT) injury; the association of the degree of DTCT injury with severity of CMS-related symptoms has not been investigated. Purpose To investigate the association between severity of CMS-related symptoms and degree and patterns of DTCT injury with use of diffusion tensor imaging (DTI), and if laterality of injury influences neurologic symptoms. Materials and Methods This retrospective case-control study used prospectively collected clinical and DTI data on patients with medulloblastoma enrolled in a clinical trial (between July 2016 and February 2020) and healthy controls (between April and November 2017), matched with the age range of the participants with medulloblastoma. CMS was divided into types 1 (CMS1) and 2 (CMS2). Multivariable logistic regression was used to investigate the relationship between CMS likelihood and DTCT injury. Results Overall, 82 participants with medulloblastoma (mean age, 11.0 years ± 5.2 [SD]; 53 male) and 35 healthy controls (mean age, 18.0 years ± 3.06; 18 female) were included. In participants with medulloblastoma, DTCT was absent bilaterally (AB), absent on the right side (AR), absent on the left side (AL), or present bilaterally (PB), while it was PB in all healthy controls. Odds of having CMS were associated with higher degree of DTCT damage (AB, odds ratio = 272.7 [95% CI: 269.68, 275.75; P < .001]; AR, odds ratio = 14.40 [95% CI: 2.84, 101.48; P < .001]; and AL, odds ratio = 8.55 [95% CI: 1.15, 74.14; P < .001). Left (coefficient = -0.07, χ2 = 12.4, P < .001) and right (coefficient = -0.15, χ2 = 33.82, P < .001) DTCT volumes were negatively associated with the odds of CMS. More participants with medulloblastoma with AB showed CMS1; unilateral DTCT absence prevailed in CMS2. Lower DTCT volumes correlated with more severe ataxia. Unilateral DTCT injury caused ipsilateral dysmetria; AB caused symmetric dysmetria. PB indicated better neurologic outcome. Conclusion The severity of CMS-associated mutism, ataxia, and dysmetria was associated with DTCT damage severity. DTCT damage patterns differed between CMS1 and CMS2. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Dorigatti Soldatelli and Ertl-Wagner in this issue.

Disease Evolution Monitored by Serial Cerebrospinal Fluid Liquid Biopsies in Two Cases of Recurrent Medulloblastoma.

Medulloblastoma is the most common malignant brain tumor in childhood. Initial treatment generally includes surgery, irradiation, and chemotherapy. Approximately 20-30% of patients will experience a recurrence, which portends a very poor prognosis. The current standard of care for evaluation for relapse includes radiographic surveillance with magnetic resonance imaging at regular intervals. The presence of circulating tumor DNA in the cerebrospinal fluid has been demonstrated to be a predictor of a higher risk of progression in a research setting for patients with medulloblastoma treated on a prospective single institution clinical trial. We have previously published and clinically validated a liquid-biopsy-based genetic assay utilizing low-pass whole genome sequencing to detect copy number alterations in circulating tumor DNA. Here, we present two teenage patients with posterior fossa medulloblastoma with recurrent disease who have been monitored with serial liquid biopsies showing tumor evolution over time, demonstrating the clinical utility of these approaches.

The effectiveness of diffusion kurtosis imaging metrics for distinguishing between brainstem glioma and cerebellar medulloblastoma.

Background: In some clinical situations, distinguishing between cerebellar medulloblastoma and brainstem glioma is important. We assessed whether diffusion kurtosis imaging (DKI) metrics could be used to distinguish cerebellar medulloblastomas from brainstem gliomas in children. Patients and methods: This prospective study was approved by the institutional review board. Seventy patients were separated into two groups according to eventual diagnosis: brainstem glioma (n = 30) and cerebellar medulloblastoma (n = 40). Both groups underwent brain magnetic resonance imaging (MRI), including DKI. The Kurtosis value for the tumor region and the ratio between Kurtosis values between the tumor and the normal parenchyma (rKurtosis) were compared between groups using the Mann-Whitney U test. Receiver operating characteristic curve analysis and the Youden's Index were applied to identify a cutoff value for distinguishing between the two tumor types, and the area under the curve (AUC), sensitivity, and specificity for the selected cutoff value were calculated. Results: Compared with brainstem gliomas, cerebellar medulloblastomas had significantly higher Kurtosis and rKurtosis values (p < 0.05). Medulloblastoma could be differentiated from brainstem gliomas using a Kurtosis value of 0.91 or an rKurtosis value of 0.90, both of which achieved 100% sensitivity, 96.7% specificity, and AUC values of 0.990. Conclusions: DKI measurements can contribute to distinguishing between cerebellar medulloblastoma and brainstem glioma in children.

Multiparametric MRI-Based Radiomics Signature with Machine Learning for Preoperative Prediction of Prognosis Stratification in Pediatric Medulloblastoma.

RATIONALE AND OBJECTIVES: Despite advances in risk-stratified treatment strategies for children with medulloblastoma (MB), the prognosis for MB with short-term recurrence is extremely poor, and there is still a lack of evaluation of short-term recurrence risk or short-term survival. This study aimed to construct and validate a radiomics model for predicting the outcome of MB based on preoperative multiparametric magnetic resonance images (MRIs) and to provide an objective for clinical decision-making. MATERIALS AND METHODS: The clinical and imaging data of 64 patients with MB admitted to Shenzhen Children's Hospital from December 2012 to December 2021 and confirmed by pathology were retrospectively collected. According to the 18-month progression-free survival, the cases were classified into a good prognosis group and a poor prognosis group, and all cases were divided into training group (70%) and validation group (30%) randomly. Radiomics features were extracted from MRI of each child. The consistency test, t-test, and the least absolute shrinkage and selection operator were used for feature selection. The support vector machine (SVM) and receiver operator characteristic were used to evaluate the distinguishing ability of the selected features to the prognostic groups. RAD score was calculated based on the selected features. The clinical characteristics and RAD score were included in the multivariate logistic regression, and prediction models were constructed by screening out independent influences. The radiomics nomogram was constructed, and its clinical significance was evaluated. RESULTS: A total of 1930 radiomic features were extracted from the images of each patient, and 11 features were included in the construction of radiomics score after selected. The area under the curve (AUC) values of the SVM model in the training and validation groups were 0.946 and 0.797, respectively. The radiomics nomogram was constructed based on the training cohort, and the AUC values in the training group and the validation group were 0.926 and 0.835, respectively. The results of clinical decision curve analysis showed that a good net benefit could be obtained from the nomogram. CONCLUSION: The radiomics nomogram established based on MRI can be used as a noninvasive predictive tool to evaluate the prognosis of children with MB, which is expected to help neurosurgeons better conduct preoperative planning and patient follow-up management.

Application of the Rotterdam postoperative cerebellar mutism syndrome prediction model in patients undergoing surgery for medulloblastoma in a single institution.

OBJECTIVE: Postoperative cerebellar mutism syndrome (CMS) develops in up to 40% of children with medulloblastoma. The Rotterdam model (RM) has been reported to predict a 66% risk of CMS in patients with a score of ≥ 100. The aim of this study was to retrospectively apply the RM to an independent cohort of patients with newly diagnosed medulloblastoma and study the applicability of the RM in predicting postoperative CMS. METHODS: Participants had to have their first tumor resection at the authors' institution and be enrolled in the SJMB12 protocol (NCT01878617). All participants underwent structured serial neurological evaluations before and then periodically after completing radiation therapy. Imaging was reviewed by the study neurologist who was blinded to CMS status when reviewing the scans and retrospectively applied RM score to each participant. RESULTS: Forty participants were included (14 females and 26 males). Four (10%) patients had CMS. The median age at tumor resection was 11.7 years (range 3.5-17.8 years). Tumor location was midline in 30 (75%), right lateral in 6 (15%), and left lateral in 4 (10%). The median Evans index was 0.3 (range 0.2-0.4), and 34 (85%) patients had an Evans index ≥ 0.3. Five participants required a ventricular shunt. The median tumor volume was 51.97 cm3 (range 20.13-180.58 cm3). Gross-total resection was achieved in 35 (87.5%) patients, near-total resection in 4 (10%), and subtotal in 1. The median RM score was 90 (range 25-145). Eighteen participants had an RM score of ≥ 100, and of these 16.7% (n = 3) had CMS. Of the 22 patients with an RM score < 100, 1 child developed CMS (4.5%, CI 0.1%-22.8%); 3 of the 18 patients with an RM score ≥ 100 developed CMS (16.7%, CI 3.6%-41.4%). The observed rate of CMS in the cohort of children with an RM score ≥ 100 was significantly lower than the observed rate in the original RM cohort (66.7%, CI 51%-80.0%, p < 0.001). A greater risk of CMS in patients with an RM score ≥ 100 could not be confirmed (p = 0.31). CONCLUSIONS: At the authors' institution, the incidence of CMS in patients who had an RM ≥ 100 was significantly lower than the RM cohort. These findings raise questions regarding generalizability of RM; however, fewer cases of CMS and a relatively small cohort limit this conclusion.

The Application of Sodium Fluorescein in Resection of Medulloblastoma Under YELLOW 560 Filter: Feasibility and Preliminary Results of a Monocentric Cohort and Systematic Review.

BACKGROUND: Maximizing surgical resection of medulloblastoma (MB) affects overall survival; nevertheless, surgical resection remains a because of the infiltrative behavior of this tumor. Several dyes have been tested for improving tumor visualization; however, few reports with different protocols of fluorophores use are available and the results are inconsistent. Hence, we report our experience with sodium fluorescein in MB surgery, aiming to assess the role of this technique on the extent of resection. Furthermore, we performed a literature review of this topic. METHODS: Fluorescence characteristics, extent of resection, and clinical outcome were analyzed in 9 consecutively operated patients with MB. A comprehensive literature search and review for English-language articles concerning fluorescein application in MB was conducted. RESULTS: In our cohort, no side effect related to fluorescein occurred; all tumors presented with an intense or moderate yellow-green enhancement, and fluorescein was judged fundamental in distinguishing tumors from viable tissue in 7 of 9 cases. Gross total resection or near-total resection (i.e., a residual tumor volume <1.5 cm3) was achieved in 8 patients. The review explored the different techniques and surgical interpretations as well as surgical radicality; we did not find a homogenous protocol for fluorescein injection in the published articles. Fluorescence appeared moderate or intense in almost all cases, with a high percentage of usefulness and consensual achievement of a high rate of gross total resection. CONCLUSIONS: Based on these results, we can infer that fluorescein-guided surgical resection is a safe and valuable method for patients with MB.

Concurrent medulloblastoma and cardiac fibroma: a rare presentation of Gorlin-Goltz syndrome.

BACKGROUND: Gorlin-Goltz syndrome is a rare autosomal dominant disorder resulting from PTCH1 gene mutation and presents with variable clinical manifestations. The co-occurrence of medulloblastoma and cardiac fibroma in Gorlin-Goltz syndrome is extremely rare. The present article discusses a patient diagnosed with Gorlin-Goltz syndrome and concurrent medulloblastoma and cardiac fibroma. CASE PRESENTATION: A 19-month-old boy transferred to our hospital after a radiological finding of posterior fossa lesion and hydrocephalus. A pericardial mass was noted after persistent arrhythmias. Both tumors were excised for definitive management. The histopathological sections were diagnostic of desmoplastic nodular medulloblastoma, WHO grade 4 and cardiac fibroma. Molecular and genetic investigations confirmed a pathogenic variant of PTCH1 gene, suggestive of autosomal dominant Gorlin-Goltz syndrome. CONCLUSION: Co-occurrence of medulloblastoma and cardiac fibroma is extremely rare and poses a management dilemma. Genetic counseling and antenatal screening are of utmost importance to early detect and manage patients with Gorlin-Goltz syndrome.

Neurocognitive and radiological follow-up of children under 5 years of age treated for medulloblastoma according to the HIT-SKK protocol.

BACKGROUND: The HIT-SKK protocol is used for low/standard-risk medulloblastomas in young children with the aim to eliminate cranial irradiation and its neuropsychological (NP) sequelae. This therapy includes IV and intraventricular (ITV) methotrexate (MTX) potentially responsible for leukoencephalopathy (LE) and neurocognitive disorders. This study describes the risk factors and course of LE, and investigates its correlation with neurocognitive impact. METHODS: A retrospective, multicenter study was conducted in 35 children under 5 years old, with a median follow-up of 72 months (range 14 to 130). The main analysis was performed in 30 patients who received cumulative doses of MTX as per-protocol (group 1). Five patients who received higher cumulative doses of MTX were analyzed separately. All follow-up MRIs and NP assessments were centrally reviewed by experts. RESULTS: Twenty patients in group 1 developed LE, grade 2 and 3 abnormalities did not correlate with higher cumulative doses of ITV-MTX (p = 0.698). Considering the most recent NP evaluation, the Full-Scale IQ (FSIQ) and Wechsler indices were in the average to lower average range. The FSIQ was deficient in 6/17 evaluable patients. Cumulative dose of ITV-MTX was almost associated with decreased processing speed competence (p = 0.055) which was the most frequently impaired neurocognitive domain. Neuropsychological assessment scores were not statistically lower in patients with persistent grade 2 LE at the end of follow-up. CONCLUSION: This study described that the use of cumulative dose of MTX (IV and ITV) according to the HIT-SKK protocol resulted in LE that tented to decrease over time, without significant correlation with a decline in neuro-intellectual skills.

MRI features of pediatric atypical teratoid rhabdoid tumors and medulloblastomas of the posterior fossa.

BACKGROUND: Atypical teratoid rhabdoid tumor (AT/RT) occurs at a younger age and is associated with a worse prognosis than medulloblastoma; however, these two tumor entities are mostly indistinguishable on neuroimaging. The aim of our study was to differentiate AT/RT and medulloblastoma based on their clinical and MRI features to enhance treatment planning and outcome prediction. METHODS: From 2005-2021, we retrospectively enrolled 16 patients with histopathologically diagnosed AT/RT and 57 patients with medulloblastoma at our institute. We evaluated their clinical data and MRI findings, including lesion signals, intratumoral morphologies, and peritumoral/distal involvement. RESULTS: The age of children with AT/RT was younger than that of children with medulloblastoma (2.8 ± 4.9 [0-17] vs. 6.5 ± 4.0 [0-18], p < 0.001), and the overall survival rate was lower (21.4% vs. 66.0%, p = 0.005). Regarding lesion signals on MRI, AT/RT had a lower ADCmin (cutoff value ≤544.7 × 10-6  mm2 /s, p < 0.001), a lower ADC ratio (cutoff value ≤0.705, p < 0.001), and a higher DWI ratio (cutoff value ≥1.595, p < 0.001) than medulloblastoma. Regarding intratumoral morphology, the "tumor central vein sign" was mostly exclusive to medulloblastoma (24/57, 42.1%; AT/RT 1/16, 6.3%; p = 0.007). Regarding peritumoral invasion on T2WI, AT/RT was more prone to invasion of the brainstem (p < 0.001) and middle cerebellar peduncle (p < 0.001) than medulloblastoma. CONCLUSIONS: MRI findings of a lower ADC value, more peritumoral invasion, and absence of the "tumor central vein sign" may be helpful to differentiate AT/RT from medulloblastoma. These distinct MRI findings together with the younger age of AT/RT patients may explain the worse outcomes in AT/RT patients.

Resection cavity auto-contouring for patients with pediatric medulloblastoma using only CT information.

PURPOSE: Target delineation for radiation therapy is a time-consuming and complex task. Autocontouring gross tumor volumes (GTVs) has been shown to increase efficiency. However, there is limited literature on post-operative target delineation, particularly for CT-based studies. To this end, we trained a CT-based autocontouring model to contour the post-operative GTV of pediatric patients with medulloblastoma. METHODS: One hundred four retrospective pediatric CT scans were used to train a GTV auto-contouring model. Eighty patients were then preselected for contour visibility, continuity, and location to train an additional model. Each GTV was manually annotated with a visibility score based on the number of slices with a visible GTV (1 = < 25%, 2 = 25-50%, 3 = > 50-75%, and 4 = > 75-100%). Contrast and the contrast-to-noise ratio (CNR) were calculated for the GTV contour with respect to a cropped background image. Both models were tested on the original and pre-selected testing sets. The resulting surface and overlap metrics were calculated comparing the clinical and autocontoured GTVs and the corresponding clinical target volumes (CTVs). RESULTS: Eighty patients were pre-selected to have a continuous GTV within the posterior fossa. Of these, 7, 41, 21, and 11 were visibly scored as 4, 3, 2, and 1, respectively. The contrast and CNR removed an additional 11 and 20 patients from the dataset, respectively. The Dice similarity coefficients (DSC) were 0.61 ± 0.29 and 0.67 ± 0.22 on the models without pre-selected training data and 0.55 ± 13.01 and 0.83 ± 0.17 on the models with pre-selected data, respectively. The DSC on the CTV expansions were 0.90 ± 0.13. CONCLUSION: We successfully automatically contoured continuous GTVs within the posterior fossa on scans that had contrast > ± 10 HU. CT-Based auto-contouring algorithms have potential to positively impact centers with limited MRI access.

Exceptionally rare IDH1-mutant adult medulloblastoma with concurrent GNAS mutation revealed by in vivo magnetic resonance spectroscopy and deep sequencing.

Medulloblastoma (MB) is the most common malignant brain tumor occurring in childhood and rarely found in adults. Based on transcriptome profile, MB are currently classified into four major molecular groups reflecting a considerable biological heterogeneity: WNT-activated, SHH-activated, group 3 and group 4. Recently, DNA methylation profiling allowed the identification of additional subgroups within the four major molecular groups associated with different clinic-pathological and molecular features. Isocitrate dehydrogenase-1 and 2 (IDH1 and IDH2) mutations have been described in several tumors, including gliomas, while in MB are rarely reported and not routinely investigated. By means of magnetic resonance spectroscopy (MRS), we unequivocally assessed the presence the oncometabolite D-2-hydroxyglutarate (2HG), a marker of IDH1 and IDH2 mutations, in a case of adult MB. Immunophenotypical work-up and methylation profiling assigned the diagnosis of MB, subclass SHH-A, and molecular testing revealed the presence of the non-canonical somatic IDH1(p.R132C) mutation and an additional GNAS mutation, also rarely described in MB. To the best of our knowledge, this is the first reported case of MB simultaneously harboring both mutations. Of note, tumor exhibited a heterogeneous phenotype with a tumor component displaying glial differentiation, with robust GFAP expression, and a component with conventional MB features and selective presence of GNAS mutation, suggesting co-existence of two different major tumor subclones. These findings drew attention to the need for a deeper genetic characterization of MB, in order to get insights into their biology and improve stratification and clinical management of the patients. Moreover, our results underlined the importance of performing MRS for the identification of IDH mutations in non-glial tumors. The use of throughput molecular profiling analysis and advanced medical imaging will certainly increase the frequency with which tumor entities with rare molecular alterations will be identified. Whether these findings have any specific therapeutic implications or prognostic relevance requires further investigations.

Placement of EVD in pediatric posterior fossa tumors: safe and efficient or old-fashioned? The Vienna experience.

PURPOSE: The perioperative treatment of hydrocephalus in pediatric posterior fossa tumors with an external ventricular drain (EVD) is the treatment of choice in our center. We analyzed our experience in using EVD concerning safety and effectivity. METHODS: This is a single-center retrospective cohort study of 100 consecutive pediatric patients who underwent resection for a newly diagnosed tumor in the posterior fossa between 2011 and 2022. RESULTS: Of the 100 patients with posterior fossa tumors, 80 patients (80%) had radiological signs of hydrocephalus at presentation, 49 patients (49%) of whom underwent placement of an EVD. In 40 patients, the EVD was inserted at a mean of 2.25 days prior to the tumor resection; 9 had the EVD inserted during tumor resection (frontal trajectory in 7 patients, occipital trajectory in 2 patients). Histology revealed pilocytic astrocytoma in 48 patients, medulloblastoma in 32, ependymoma in 11, and other histologic entities in 9 patients. Gross total/near-total resection was achieved in 46 (95.83%) of the 48 pilocytic astrocytomas, 30 (93.75%) of the 32 medulloblastomas, and 11 (100%) of the 11 ependymomas. The mean number of total days with the EVD in place was 8.61 ± 3.82 (range 2-16 days). The mean number of days with an EVD after tumor resection was 6.35 ± 3.8 (range 0-16 days). EVD-associated complications were seen in 6 patients (12.24%) including one infection. None of these resulted in a worse clinical course or any long-term sequelae. Permanent CSF diversion at 6 months after surgery was necessary in 13 patients (13%), including two VP shunt, two SD-shunt, six endoscopic third ventriculostomy (ETV), and three combined VP shunt and ETV procedures. Patients with a medulloblastoma or ependymoma had a higher rate of permanent CSF diversion needed than the group of pilocytic astrocytoma patients (27.9% versus 2.13%, p < 0.001). In patients with metastatic disease, 7 of 17 patients (41.18%) needed a permanent CSF diversion, compared to 6 of 83 patients (7.23%) in the group without metastasis (p = 0.001). CONCLUSION: The treatment of hydrocephalus in pediatric posterior fossa tumors with an EVD as a temporary measure is safe and effective, provided that a multi-professional understanding for its handling is given and there is no need for a long transport of the children.

Differentiating between adult intracranial medulloblastoma and ependymoma using MRI.

AIM: To investigate the value of routine magnetic resonance imaging (MRI) examination combined with diffusion-weighted imaging (DWI) in the differential diagnosis of adult intracranial medulloblastomas and ependymomas. MATERIALS AND METHODS: MRI images of 18 medulloblastomas and 18 ependymomas in adult patients were analysed retrospectively, and the differences in MRI features of lesions and apparent diffusion coefficient (ADC) of solid lesions between the two groups were recorded. Independent sample t-tests and χ2 tests were used to analyse the differences in MRI signs and maximum ADC (ADCmax), minimum ADC (ADCmin), and mean ADC (ADCmean) values between the two groups. The receiver operating characteristic (ROC) curve was used to determine the differential diagnostic efficacy and optimal threshold for each ADC value. RESULTS: Age, tumour location, and tumour enhancement were significantly different between adult medulloblastoma and ependymoma (p<0.05). The ADCmax (0.69 ± 0.11 versus 1.04 ± 0.20 × 10-3 mm2/s, p<0.001), ADCmin (0.57 ± 0.12 versus 0.96 ± 0.21 × 10-3 mm2/s, p<0.001), and ADCmean (0.62 ± 0.11 versus 1.00 ± 0.20 × 10-3 mm2/s, p<0.001) values were significantly lower in adult medulloblastoma than in ependymoma. The areas under the ROC curves of ADCmax, ADCmin, and ADCmean were 0.951, 0.957, and 0.966, respectively. The optimal ADCmean threshold was 0.75 × 10-3 mm2/s, with a sensitivity of 88.9% and a specificity of 88.9%. CONCLUSION: Routine MRI examination combined with DWI helps differentiate between intracranial infratentorial medulloblastoma and ependymoma in adults.

Radiomics-based machine learning models for prediction of medulloblastoma subgroups: a systematic review and meta-analysis of the diagnostic test performance.

BACKGROUND: Medulloblastomas are a major cause of cancer-related mortality in the pediatric population. Four molecular groups have been identified, and these molecular groups drive risk stratification, prognostic modeling, and the development of novel treatment modalities. It has been demonstrated that radiomics-based machine learning (ML) models are effective at predicting the diagnosis, molecular class, and grades of CNS tumors. PURPOSE: To assess radiomics-based ML models' diagnostic performance in predicting medulloblastoma subgroups and the methodological quality of the studies. MATERIAL AND METHODS: A comprehensive literature search was performed on PubMed; the last search was conducted on 1 May 2022. Studies that predicted all four medulloblastoma subgroups in patients with histopathologically confirmed medulloblastoma and reporting area under the curve (AUC) values were included in the study. The quality assessments were conducted according to the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) and Checklist for Artificial Intelligence in Medical Imaging (CLAIM). A meta-analysis of radiomics-based ML studies' diagnostic performance for the preoperative evaluation of medulloblastoma subgrouping was performed. RESULTS: Five studies were included in this meta-analysis. Regarding patient selection, two studies indicated an unclear risk of bias according to the QUADAS-2. The five studies had an average CLAIM score and compliance score of 23.2 and 0.57, respectively. The meta-analysis showed pooled AUCs of 0.88, 0.82, 0.83, and 0.88 for WNT, SHH, group 3, and group 4 for classification, respectively. CONCLUSION: Radiomics-based ML studies have good classification performance in predicting medulloblastoma subgroups, with AUCs >0.80 in every subgroup. To be applied to clinical practice, they need methodological quality improvement and stability.

MRI Radiomics Signature of Pediatric Medulloblastoma Improves Risk Stratification Beyond Clinical and Conventional MR Imaging Features.

BACKGROUND: Prognostic evaluation is important for personalized treatment in children with medulloblastoma (MB). Limited data are available for risk stratification using a radiomics-based model. PURPOSE: To evaluate the incremental value of an MRI radiomics signature in stratifying the risk of pediatric MB in terms of overall survival (OS). STUDY TYPE: Retrospective. SUBJECTS: A total of 111 children (mean age 5.82 years) with pathologically confirmed MB divided into training and validation cohorts (77 and 34 children, respectively). FIELD STRENGTH/SEQUENCE: A 3 T, contrast-enhanced T1-weighted imaging with inversion recovery. ASSESSMENT: The study endpoint was OS defined as the time between the preoperative MRI study and death or last follow-up. The radiomics signature model and a clinical-MRI model were developed for personalized OS prediction. An integrative model, which combined the radiomics signature and clinical-MRI features, was also built using multivariable Cox regression model. The performance of the three models was evaluated with the C-index. The performance of integrative model was assessed by calibration curve and decision curve analysis (DCA). STATISTICAL TESTS: Independent T-test, Mann-Whitney U test, Fisher's exact tests or chi-square test, logistic regression analysis, Kaplan-Meier survival analysis, C-index, intraclass correlation coefficients (ICC). P < 0.05 was considered statistically significant. RESULTS: The media OS was 2.83 years (3.87 ± 1.85 years). Two clinical and one conventional MR imaging features (remnant, adjuvant treatment, and peritumoral edema) were selected for clinical-MRI model building. The integrative model evaluated OS (C-index 0.823) better than either the radiomics signature (C-index 0.702) or the clinical-MRI model (C-index 0.771). And it also showed good performance in the validation cohort (C-indices: 0.786, 0.756, 0.721), which was validated by the good calibration (P > 0.05) and more benefit. DATA CONCLUSIONS: This study demonstrated that the integrative model, which combined radiomics signature, clinical, and conventional MRI features, showed best performance in OS evaluation for children with MB. The radiomics signature may confer incremental value over clinical-MRI features. EVIDENCE LEVEL: 3. TECHNICAL EFFICACY: Stage 2.

Prenatally detected congenital medulloblastoma.

We describe a congenital cerebellar mass in a fetus at 30 weeks GA. The lesion is detected at the prenatal third-trimester ultrasound, confirmed by fetal MRI, and determined as medulloblastoma in postmortem pathologic evaluation.

Differentiation of pilocytic astrocytoma, medulloblastoma, and hemangioblastoma on diffusion-weighted and dynamic susceptibility contrast perfusion MRI.

This study aimed to evaluate the diagnostic performance of dynamic susceptibility contrast (DSC) perfusion magnetic resonance imaging and apparent diffusion coefficient (ADC) for differentiating common posterior fossa tumors, pilocytic astrocytoma (PA), medulloblastoma (MB), and hemangioblastoma (HB). Between January 2016 and April 2022, we enrolled 23 (median age, 7 years [range, 2-26]; 12 female), 13 (10 years [1-24]; 3 female), and 12 (43 years [23-73]; 7 female) patients with PA, MB, and HB, respectively. Normalized relative cerebral blood volume and flow (nrCBV and nrCBF) and normalized mean ADC (nADCmean) were calculated from volume-of-interest and statistically compared. nADCmean was significantly higher in PA than in MB (PA: median, 2.2 [range, 1.59-2.65] vs MB: 0.93 [0.70-1.37], P < .001). nrCBF was significantly higher in HB than in PA and MB (PA: 1.10 [0.54-2.26] vs MB: 1.62 [0.93-3.16] vs HB: 7.83 [2.75-20.1], all P < .001). nrCBV was significantly different between all 3 tumor types (PA: 0.89 [0.34-2.28] vs MB: 1.69 [0.93-4.23] vs HB: 8.48 [4.59-16.3], P = .008 for PA vs MB; P < .001 for PA vs HB and MB vs HB). All tumors were successfully differentiated using an algorithmic approach with a threshold value of 4.58 for nrCBV and subsequent threshold value of 1.38 for nADCmean. DSC parameters and nADCmean were significantly different between PA, MB, and HB. An algorithmic approach combining nrCBV and nADCmean may be useful for differentiating these tumor types.

Low apparent diffusion coefficient in an extracranial brain tumor: a case report.

BACKGROUND: Medulloblastoma is well known as the most common malignant brain tumor identified in children, frequently found at an intra-axial location in the posterior cranial fossa. Extra-axial medulloblastoma is uncommon and often misdiagnosed. We believe that a thorough understanding of atypical medulloblastoma cases is important in daily practice. CASE PRESENTATION: We present the unique case of a 39-year-old woman of Asian descent who suffered from headaches and right-sided hearing impairment. A right extra-axial medulloblastoma with an extremely low apparent diffusion coefficient of 0.404 × 10-3 mm2/second was detected on magnetic resonance imaging. The initial diagnosis suggested schwannoma or hemangioblastoma. However, the postoperative histopathologic findings indicated medulloblastoma (World Health Organization grade IV). Pre- and postoperative magnetic resonance imaging revealed no drop metastasis, but adjuvant radiation therapy was still required as a standard treatment therapy CONCLUSIONS: Extra-axial medulloblastoma is an uncommon tumor that is often mistaken for other cerebellopontine angle neoplasms. We describe a rare example of extra-axial medulloblastoma, characterized by a low apparent diffusion coefficient. When evaluating an atypical cerebellopontine angle neoplasm, the apparent diffusion coefficient should be considered a relevant indicator.

The role of apparent diffusion coefficient histogram metrics for differentiating pediatric medulloblastoma histological variants and molecular groups.

BACKGROUND: Medulloblastoma, a high-grade embryonal tumor, is the most common primary brain malignancy in the pediatric population. Molecular medulloblastoma groups have documented clinically and biologically relevant characteristics. Several authors have attempted to differentiate medulloblastoma molecular groups and histology variants using diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps. However, literature on the use of ADC histogram analysis in medulloblastomas is still scarce. OBJECTIVE: This study presents data from a sizable group of pediatric patients with medulloblastoma from a single institution to determine the performance of ADC histogram metrics for differentiating medulloblastoma variants and groups based on both histological and molecular features. MATERIALS AND METHODS: In this retrospective study, we evaluated the distribution of absolute and normalized ADC values of medulloblastomas. Tumors were manually segmented and diffusivity metrics calculated on a pixel-by-pixel basis. We calculated a variety of first-order histogram metrics from the ADC maps, including entropy, minimum, 10th percentile, 90th percentile, maximum, mean, median, skewness and kurtosis, to differentiate molecular and histological variants. ADC values of the tumors were also normalized to the bilateral cerebellar cortex and thalami. We used the Kruskal-Wallis and Mann-Whitney U tests to evaluate differences between the groups. We carried out receiver operating characteristic (ROC) curve analysis to evaluate the areas under the curves and to determine the cut-off values for differentiating tumor groups. RESULTS: We found 65 children with confirmed histopathological diagnosis of medulloblastoma. Mean age was 8.3 ± 5.8 years, and 60% (n = 39) were male. One child was excluded because histopathological variant could not be determined. In terms of medulloblastoma variants, tumors were classified as classic (n = 47), desmoplastic/nodular (n = 9), large/cell anaplastic (n = 6) or as having extensive nodularity (n = 2). Seven other children were excluded from the study because of incomplete imaging or equivocal molecular diagnosis. Regarding medulloblastoma molecular groups, there were: wingless (WNT) group (n = 7), sonic hedgehog (SHH) group (n = 14) and non-WNT/non-SHH (n = 36). Our results showed significant differences among the molecular groups in terms of the median (P = 0.002), mean (P = 0.003) and 90th percentile (P = 0.002) ADC histogram metrics. No significant differences among the various medulloblastoma histological variants were found. CONCLUSION: ADC histogram analysis can be implemented as a complementary tool in the preoperative evaluation of medulloblastoma in children. This technique can provide valuable information for differentiating among medulloblastoma molecular groups. ADC histogram metrics can help predict medulloblastoma molecular classification preoperatively.