The performance of diffusion tensor imaging parameters for the distinction between medulloblastoma and pilocytic astrocytoma

BACKGROUND

The aim of this study was to evaluate the performance of diffusion tensor imaging (DTI) parameters for the distinction between pediatric medulloblastomas and pilocytic astrocytomas.

METHODS

DTI was performed in 36 patients, who were divided into two groups: group 1 consisted of 26 patients with medulloblastoma, whereas group 2 consisted of 10 patients with pilocytic astrocytoma. The Mann-Whitney U Test was utilized to compare the tumoral fractional anisotropy (tFA) and diffusivity (tMD) values and the tumor to parenchyma ratios for these values (rFA and rMD, respectively) between these two groups. Receiver operating characteristic (ROC) curve analysis and the Youden Index were applied to compute the cut-off point, and then the area under the curve (AUC), sensitivity, and specificity were calculated.

RESULTS

The tFA and rFA values of group 1 were significantly higher than those of group 2 (P<0.05). In contrast, the tMD and rMD values of group 1 were significantly lower than those of group 2 (P<0.05). Among the FA parameters, a cut-off tFA value of 0.37 provided the best ability to discriminate between medulloblastomas and pilocytic astrocytomas, producing a sensitivity value of 84.6%, a specificity of 80%, and an AUC of 81.7%. The cut-off values for MD and rMD were determined to be 1.06 × 10-3 mm2/s and 1.33, respectively, and were determined to be the most efficacious parameters for the differential diagnosis between medulloblastoma and pilocytic astrocytoma, which generated sensitivity, specificity, and AUC values of 100%.

CONCLUSIONS

DTI parameters can play pivotal roles in the discrimination between medulloblastoma and pilocytic astrocytoma.

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.

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.

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 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.

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.

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.

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.

Application of Apparent Diffusion Coefficient Histogram Metrics for Differentiation of Pediatric Posterior Fossa Tumors : A Large Retrospective Study and Brief Review of Literature

PURPOSE

This study aimed to evaluate the application of apparent diffusion coefficient (ADC) histogram analysis to differentiate posterior fossa tumors (PFTs) in children.

METHODS

A total of 175 pediatric patients with PFT, including 75 pilocytic astrocytomas (PA), 59 medulloblastomas, 16 ependymomas, and 13 atypical teratoid rhabdoid tumors (ATRT), were analyzed. Tumors were visually assessed using DWI trace and conventional MRI images and manually segmented and post-processed using parametric software (pMRI). Furthermore, tumor ADC values were normalized to the thalamus and cerebellar cortex. The following histogram metrics were obtained: entropy, minimum, 10th, and 90th percentiles, maximum, mean, median, skewness, and kurtosis to distinguish the different types of tumors. Kruskal Wallis and Mann-Whitney U tests were used to evaluate the differences. Finally, receiver operating characteristic (ROC) curves were utilized to determine the optimal cut-off values for differentiating the various PFTs.

RESULTS

Most ADC histogram metrics showed significant differences between PFTs (p < 0.001) except for entropy, skewness, and kurtosis. There were significant pairwise differences in ADC metrics for PA versus medulloblastoma, PA versus ependymoma, PA versus ATRT, medulloblastoma versus ependymoma, and ependymoma versus ATRT (all p < 0.05). Our results showed no significant differences between medulloblastoma and ATRT. Normalized ADC data showed similar results to the absolute ADC value analysis. ROC curve analysis for normalized ADC_median values to thalamus showed 94.9% sensitivity (95% CI: 85-100%) and 93.3% specificity (95% CI: 87-100%) for differentiating medulloblastoma from ependymoma.

CONCLUSION

ADC histogram metrics can be applied to differentiate most types of posterior fossa tumors in children.

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.

Pediatric synchronous multifocal and disseminated cerebrospinal classic medulloblastoma revealed by bilateral decreased visual acuity: a case report

Medulloblastoma (MB) is a rapidly growing malignant solid tumor that arises from stem cells located in the subependymal germinal matrix or outer granular layer of the cerebellum. It represents 15 to 30% of pediatric brain tumors and less than 1% of primary brain tumors. The reason for the high incidence of MB in children compared to adults is the embryonic origin of the tumor. In typical cases, MB manifests as a solitary lesion in the fourth ventricle or in the cerebellar parenchyma; cases of synchronous multifocal and disseminated MB are quite rare in patients without familial tumor syndromes. To date, only 7 cases in adults and a single pediatric case with Gorlin syndrome have been described previously. Here, the authors report a new case of synchronous multifocal classic cerebrospinal histologically confirmed MB in a 10-year-old male patient revealed by bilateral decreased visual acuity without any other localizing neurological signs. The authors will proceed with a review of the current literature regarding this rare entity.

Neurogenic stunned myocardium resulting from surgical brainstem handling during resection of paediatric recurrent medulloblastoma-a possible brain heart interaction

BACKGROUND

Neurogenic stunned myocardium (NSM) is characterised by an acute onset cardiac dysfunction following an acute neurological insult which mimics acute coronary syndrome.

CASE DETAILS

A 12-year-old male child was admitted to the neuro-intensive care unit (NICU) following midline suboccipital craniotomy and resection of recurrent medulloblastoma. Postoperatively, in NICU, he developed tachycardia and hypotension, which was unresponsive to fluid challenge requiring norepinephrine infusion. Intraoperatively, during tumour resection from the dorsal medulla, episodes of hypertension and bradycardia were observed. Intraoperative blood loss was adequately managed with a stable hemodynamic profile without postoperative anaemia. An electrocardiogram showed sinus tachycardia with T wave inversion, and blood investigation revealed elevated cardiac troponin T levels. Point of care ultrasound (POCUS) of heart and lung showed features of NSM. Infusion dobutamine was added to achieve a target mean arterial pressure of 65 mm Hg with concomitant furosemide infusion and fluid restriction. Daily POCUS assessment of cardiac contractility and volume status was done. The patient was weaned from vasoactive drugs and ventilator following improvement of cardiac function and was discharged from NICU after 17 days.

CONCLUSION

NSM results from the excessive release of catecholamines following stimulation of trigger zones in the brain. To date, a handful of cases of pediatric NSM following primary brain tumour are reported where hydrocephalus resulted in trigger zone activation. In this presented case, direct brain stem stimulation during tumour resection might have triggered NSM. Irrespective of the cause, timely diagnosis and execution of supportive management in our patient resulted in a positive outcome.

MRI Radiogenomics of Pediatric Medulloblastoma: A Multicenter Study

Background Radiogenomics of pediatric medulloblastoma (MB) offers an opportunity for MB risk stratification, which may aid therapeutic decision making, family counseling, and selection of patient groups suitable for targeted genetic analysis. Purpose To develop machine learning strategies that identify the four clinically significant MB molecular subgroups. Materials and Methods In this retrospective study, consecutive pediatric patients with newly diagnosed MB at MRI at 12 international pediatric sites between July 1997 and May 2020 were identified. There were 1800 features extracted from T2- and contrast-enhanced T1-weighted preoperative MRI scans. A two-stage sequential classifier was designed-one that first identifies non-wingless (WNT) and non-sonic hedgehog (SHH) MB and then differentiates therapeutically relevant WNT from SHH. Further, a classifier that distinguishes high-risk group 3 from group 4 MB was developed. An independent, binary subgroup analysis was conducted to uncover radiomics features unique to infantile versus childhood SHH subgroups. The best-performing models from six candidate classifiers were selected, and performance was measured on holdout test sets. CIs were obtained by bootstrapping the test sets for 2000 random samples. Model accuracy score was compared with the no-information rate using the Wald test. Results The study cohort comprised 263 patients (mean age ± SD at diagnosis, 87 months ± 60; 166 boys). A two-stage classifier outperformed a single-stage multiclass classifier. The combined, sequential classifier achieved a microaveraged F1 score of 88% and a binary F1 score of 95% specifically for WNT. A group 3 versus group 4 classifier achieved an area under the receiver operating characteristic curve of 98%. Of the Image Biomarker Standardization Initiative features, texture and first-order intensity features were most contributory across the molecular subgroups. Conclusion An MRI-based machine learning decision path allowed identification of the four clinically relevant molecular pediatric medulloblastoma subgroups. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Chaudhary and Bapuraj in this issue.

The impact of ADC-histogram parameters on the discrimina-tion between medulloblastoma, ependymoma, and pilocytic astrocytoma

PURPOSE

Histograms can be determined throughout tumors, relying partly on existing tumor microstructure knowledge and the sampling effect from area of interest analyses. We aimed to investigate the impact of ADC histogram parameters in discriminating medulloblastoma, ependymoma, and pilocytic astrocytoma.

METHODS

This study received approval from the Institutional Ethics Review Committee of Children's Hospital 02. Processes were conducted according to relevant laws and regulations, and requirements for written informed consent were fulfilled. The study involved 24 patients at Children's Hospital 02 from February-December 2019. Group 1 included 12 children with medulloblastoma, group 2 included 5 with ependymoma, and group 3 included 7 with pilocytic astrocytoma. All patients underwent MRI followed by surgery or biopsy to obtain histopathological confirmations.

RESULTS

Our analysis indicated that AUC, sensitivity, and specificity were 96.7%, 91.7%, and 100%, respectively when ADCkurtosis (cut-off point = 2.34) was taken to differentiate between medulloblasto-mas and ependymomas. To distinguish between medulloblastomas and pilocytic astrocytomas, the cut-off points of ADCmean, ADCmedian, ADCmax, ADCmin, rADCmean, rADCmax, and rADCmin of 0.985, 0.910, 1.305, 0.710, 1.349, 1.738, and 1.251, were taken respectively with AUC, sensitivity, and specificity elicited at 100%. To discriminate between ependymomas and pilocytic astrocytomas, the cut-off points of ADCmean, ADCmedian, ADCmax, ADCmin, rADCmean, rADC-median, rADCmax and rADCmin were 1.010, 0.930, 1.270, 0.735, 1.346, 1.324, 1.676, and 1.273, respectively, with AUC, sensitivity, and specificity at 100%.

CONCLUSION

ADC histograms can facilitate differentiation among juvenile medulloblastoma, ependymoma, and pilocytic astrocytoma, providing reliable, objective evidence of tumor differentiation.

Case of Adult Metastatic Medulloblastoma Demonstrated on 18F-DOPA PET/CT

ABSTRACT

18F-DOPA is a promising radiotracer used for both staging and restaging of primary brain tumors based on increased transport via the L-type large neutral amino acid transport system in tumor cells. Adult medulloblastoma is extremely rare. We present a case of 25-year-old man with posterior fossa medulloblastoma treated with surgery followed by chemotherapy and radiotherapy 5 years back, which later developed metastasis to left cerebral lobe treated with gamma knife followed by surgical debulking. Recent 18F-DOPA PET/CT demonstrates recurrence and disease progression on follow-up scan. 18F-DOPA PET/CT is extremely useful for characterizing brain tumors, response assessment, and prognosis.

Recurrent Wnt medulloblastoma treated with marrow-ablative chemotherapy and autologous hematopoietic progenitor cell rescue: a dual case report and review of the literature

Wnt-activated medulloblastoma (MB) confers an excellent prognosis. However, specific treatment strategies for patients with relapsed Wnt-MB are unknown. We report two patients with recurrent beta-catenin nucleopositive Wnt-MB successfully treated by incorporating marrow-ablative chemotherapy and autologous hematopoietic progenitor cell rescue (HDCx/AuHPCR). We also present a review of the literature for previously reported cases of relapsed Wnt-MB. We propose that patients with recurrent Wnt-MB may be treated using a multi-disciplinary approach that includes HDCx/AuHPCR with or without re-irradiation.

Deep learning-based automatic tumor burden assessment of pediatric high-grade gliomas, medulloblastomas, and other leptomeningeal seeding tumors

BACKGROUND

Longitudinal measurement of tumor burden with magnetic resonance imaging (MRI) is an essential component of response assessment in pediatric brain tumors. We developed a fully automated pipeline for the segmentation of tumors in pediatric high-grade gliomas, medulloblastomas, and leptomeningeal seeding tumors. We further developed an algorithm for automatic 2D and volumetric size measurement of tumors.

METHODS

The preoperative and postoperative cohorts were randomly split into training and testing sets in a 4:1 ratio. A 3D U-Net neural network was trained to automatically segment the tumor on T1 contrast-enhanced and T2/FLAIR images. The product of the maximum bidimensional diameters according to the RAPNO (Response Assessment in Pediatric Neuro-Oncology) criteria (AutoRAPNO) was determined. Performance was compared to that of 2 expert human raters who performed assessments independently. Volumetric measurements of predicted and expert segmentations were computationally derived and compared.

RESULTS

A total of 794 preoperative MRIs from 794 patients and 1003 postoperative MRIs from 122 patients were included. There was excellent agreement of volumes between preoperative and postoperative predicted and manual segmentations, with intraclass correlation coefficients (ICCs) of 0.912 and 0.960 for the 2 preoperative and 0.947 and 0.896 for the 2 postoperative models. There was high agreement between AutoRAPNO scores on predicted segmentations and manually calculated scores based on manual segmentations (Rater 2 ICC = 0.909; Rater 3 ICC = 0.851). Lastly, the performance of AutoRAPNO was superior in repeatability to that of human raters for MRIs with multiple lesions.

CONCLUSIONS

Our automated deep learning pipeline demonstrates potential utility for response assessment in pediatric brain tumors. The tool should be further validated in prospective studies.

MRI Correlates of Ototoxicity in the Auditory Pathway in Children Treated for Medulloblastoma

OBJECTIVE

To assess diffusion and perfusion changes of the auditory pathway in pediatric medulloblastoma patients exposed to ototoxic therapies.

STUDY DESIGN

Retrospective cohort study.

SETTING

A single academic tertiary children's hospital.

PATIENTS

Twenty pediatric medulloblastoma patients (13 men; mean age 12.0 ± 4.8 yr) treated with platinum-based chemotherapy with or without radiation and 18 age-and-sex matched controls were included. Ototoxicity scores were determined using Chang Ototoxicity Grading Scale.

INTERVENTIONS

Three Tesla magnetic resonance was used for diffusion tensor and arterial spin labeling perfusion imaging.

MAIN OUTCOME MEASURES

Quantitative diffusion tensor metrics were extracted from the Heschl's gyrus, auditory radiation, and inferior colliculus. Arterial spin labeling perfusion of the Heschl's gyrus was also examined.

RESULTS

Nine patients had clinically significant hearing loss, or Chang grades more than or equal to 2a; 11 patients had mild/no hearing loss, or Chang grades less than 2a. The clinically significant hearing loss group showed reduced mean diffusivity in the Heschl's gyrus (p = 0.018) and auditory radiation (p = 0.037), and decreased perfusion in the Heschl's gyrus (p = 0.001). Mild/no hearing loss group showed reduced mean diffusivity (p = 0.036) in Heschl's gyrus only, with a decrease in perfusion (p = 0.008). There were no differences between groups in the inferior colliculus. There was no difference in fractional anisotropy between patients exposed to ototoxic therapies and controls.

CONCLUSIONS

Patients exposed to ototoxic therapies demonstrated microstructural and physiological alteration of the auditory pathway. The present study shows proof-of-concept use of diffusion tensor imaging to gauge ototoxicity along the auditory pathway. Future larger cohort studies are needed to assess significance of changes in diffusion tensor imaging longitudinally, and the relationship between these changes and hearing loss severity and longitudinal changes of the developing auditory white matter.

Association Between Brain Substructure Dose and Cognitive Outcomes in Children With Medulloblastoma Treated on SJMB03: A Step Toward Substructure-Informed Planning

PURPOSE

To characterize the association between neurocognitive outcomes (memory and processing speed) and radiation (RT) dose to the hippocampus, corpus callosum (CC), and frontal white matter (WM) in children with medulloblastoma treated on a prospective study, SJMB03.

PATIENTS AND METHODS

Patients age 3-21 years with medulloblastoma were treated at a single institution on a phase III study. The craniospinal RT dose was 23.4 Gy for average-risk patients and 36-39.6 Gy for high-risk patients. The boost dose was 55.8 Gy to the tumor bed. Patients underwent cognitive testing at baseline and once yearly for 5 years. Performance on tests of memory (associative memory and working memory) and processing speed (composite processing speed and perceptual speed) was analyzed. Mixed-effects models were used to estimate longitudinal trends in neurocognitive outcomes. Reliable change index and logistic regression were used to define clinically meaningful neurocognitive decline and identify variables associated with decline.

RESULTS

One hundred and twenty-four patients were eligible for inclusion, with a median neurocognitive follow-up of 5 years. Mean right and left hippocampal doses were significantly associated with decline in associative memory in patients without posterior fossa syndrome (all P < .05). Mean CC and frontal WM doses were significantly associated with decline in both measures of processing speed (all P < .05). Median brain substructure dose-volume histograms were shifted to the right for patients with a decline in associative memory or processing speed. The odds of decline in associative memory and composite processing speed increased by 23%-26% and by 10%-15% for every 1-Gy increase in mean hippocampal dose and mean CC or frontal WM dose, respectively.

CONCLUSION

Increasing RT dose to the CC or frontal WM and hippocampus is associated with worse performance on tests of processing speed and associative memory, respectively. Brain substructure-informed RT planning may mitigate neurocognitive impairment.

Magnetic Resonance Imaging in the Contemporary Management of Medulloblastoma: Current and Emerging Applications

Medulloblastoma, the most common malignant primary brain tumor in children, is now considered to comprise of four distinct molecular subgroups-wingless (WNT), sonic hedgehog (SHH), Group 3, and Group 4 medulloblastoma, each associated with distinct developmental origins, unique transcriptional profiles, diverse phenotypes, and variable clinical behavior. Due to its exquisite anatomic resolution, multiparametric nature, and ability to image the entire craniospinal axis, magnetic resonance imaging (MRI) is the preferred and recommended first-line imaging modality for suspected brain tumors including medulloblastoma. Preoperative MRI can reliably differentiate medulloblastoma from other common childhood posterior fossa masses such as ependymoma, pilocytic astrocytoma, and brainstem glioma. On T1-weighted images, medulloblastoma is generally iso- to hypointense, while on T2-weighted images, the densely packed cellular component of the tumor is significantly hypointense and displays restricted diffusion on diffusion-weighted imaging. Following intravenous gadolinium, medulloblastoma shows significant but variable and heterogeneous contrast enhancement. Given the propensity of neuraxial spread in medulloblastoma, sagittal fat-suppressed T1-postcontrast spinal MRI is recommended to rule out leptomeningeal metastases for accurate staging. Following neurosurgical excision, postoperative MRI done within 24-48 h confirms the extent of resection, accurately quantifying residual tumor burden imperative for risk assignment. Post-treatment MRI is needed to assess response and effectiveness of adjuvant radiotherapy and systemic chemotherapy. After completion of planned therapy, surveillance MRI is recommended periodically on follow-up for early detection of recurrence for timely institution of salvage therapy, as well as for monitoring treatment-related late complications. Recent studies suggest that preoperative MRI can reliably identify SHH and Group 4 medulloblastoma but has suboptimal predictive accuracy for WNT and Group 3 tumors. In this review, we focus on the role of MRI in the diagnosis, staging, and quantifying residual disease; post-treatment response assessment; and periodic surveillance, and provide a brief summary on radiogenomics in the contemporary management of medulloblastoma.

Metastatic Medulloblastoma: 18F-FDG and 68Ga-DOTANOC PET/CT in Response Evaluation

ABSTRACT

We describe the utility of molecular imaging with 18F-FDG and 68Ga-DOTANOC PET for treatment response assessment in a case of metastatic medulloblastoma. 18F-FDG and 68Ga-DOTANOC PET/CT revealed extensive metastases to bone and bone marrow. Patient subsequently had an excellent response to systemic chemotherapy which was evidenced by resolution of tracer-avid skeletal lesions on both FDG and DOTANOC PET/CT.

Clinical-MRI radiomics enables the prediction of preoperative cerebral spinal fluid dissemination in children with medulloblastoma

BACKGROUND

Medulloblastoma (MB) is the most common pediatric embryonal tumor. Accurate identification of cerebral spinal fluid (CSF) dissemination is important in prognosis prediction. Both MRI of the central nervous system (CNS) and CSF cytology will appear false positive and negative. Our objective was to investigate the added value of preoperative-enhanced T1-weighted image-based radiomic features to clinical characteristics in predicting preoperative CSF dissemination for children with MB.

MATERIALS AND METHODS

This retrospective study included 84 children with histopathologically confirmed MB between November 2006 and November 2018 (training cohort, n=60; internal validation cohort, n=24). A set of cases between December 2018 and February 2020 were used for external validation (n=40). The children with normal head and spine magnetic resonance images (MRI) and no subsequent dissemination in 1 year were diagnosed as non-CSF dissemination. The CSF dissemination was manifested as intracranial or intraspinal nodular-enhanced lesions. Clinical features were collected, and conventional MRI features of preoperative head MRI examinations were evaluated. A total of 385 radiomic features were extracted from preoperative-enhanced T1-weighted images. Minimum redundancy, maximum correlation, and least absolute shrinkage and selection operator were performed to select the features with the best performance in predicting preoperative CSF dissemination. A combined clinical-MRI radiomic prediction model was developed using multivariable logistic regression. Receiver operating curve analysis (ROC) was used to validate the predictive performance. Nomogram and decision curve analysis (DCA) were developed to evaluate the clinical utility of the combined model.

RESULTS

One clinical and nine radiomic features were selected for predicting preoperative CSF dissemination. The combined model incorporating clinical and radiomic features had the best predictive performance in the training cohort with an AUC of 0.89. This was validated in the internal and external cohorts with AUCs of 0.87 and 0.73. The clinical utility of the model was confirmed by a clinical-MRI radiomic nomogram and DCA.

CONCLUSIONS

The combined model incorporating clinical, conventional MRI, and radiomic features could be applied to predict preoperative CSF dissemination for children with MB as a noninvasive biomarker, which could aid in risk evaluation.

Resection of a recurrent medulloblastoma in the anterior middle part of the aqueduct with a flexible endoscope: a case report

Resection or biopsy of intraventricular brain tumors using an endoscope has become common, but the limitations of these procedures are not clear. Manipulation to access a tumor that arises from the blind angle of the rigid endoscope, such as the anterior part of the aqueduct, is limited. We report here that we successfully resected a recurrent medulloblastoma in the anterior part of the aqueduct using only a flexible endoscope. This method appears to be suitable for poorly vascularized and suctionable tumors that arise in the blind angle of a rigid endoscope.

Surgical management of posterior fossa medulloblastoma in children: The Lyon experience

INTRODUCTION

Modern approach for the treatment of posterior fossa medulloblastomas remains a challenge for pediatric neurosurgeons and pediatric oncologists and requires a multidisciplinary approach to optimize survival and clinical results.

MATERIAL AND METHODS

We report the surgical principles of the treatment of posterior fossa medulloblastomas in children and how to avoid technical mistakes especially in very young patients. We also report our experience in a series of 64 patients operated from a medulloblastoma between 2000 and 2018 in Lyon.

RESULTS

All patients had a craniospinal MRI. Eighty-one percent of the patients (n=50) had strictly midline tumor while 19% (n=14) had lateralized one. Eleven percent (n=7) had metastasis at diagnosis on the initial MRI. Forty-one percent (n=29) had an emergency ETV to treat hydrocephaly and the intracranial hypertension. All patient underwent a direct approach and a complete removal was achieved in 78% (n=58) of the cases on the postoperative MRI realized within 48h postsurgery. Histological findings revealed classical medulloblastoma in 73% (n=46), desmoplastic medulloblastoma in 17% (n=11) and anaplastic/large cell medulloblastoma in 10% (n=7). Patients were classified as low risk in 7 cases, standard risk in 30 cases and high risk in 27 cases. Ninety-six percent (n=61) of the patient received radiotherapy. Seventy-six percent (n=48) received pre-irradiation or adjuvant chemotherapy. At last follow-up in December 2018, 65% (n=41) of the patient were in complete remission, 12% (n=8) were in relapse and 27% (n=15) had died from their disease. The overall survival at five , ten and fifteen years for all the series was of 76%, 73% and 65.7% respectively.

CONCLUSIONS

Medulloblastomas remain a chimiosensible and radiosensible disease and the complete surgical removal represents a favorable prognostic factor. The extension of surgery has also to be weighted in consideration of the new biomolecular and genetic knowledge that have to be integrated by surgeons to improve quality of life of patients.

Mapping of long-term cognitive and motor deficits in pediatric cerebellar brain tumor survivors into a cerebellar white matter atlas

PURPOSE

Diaschisis of cerebrocerebellar loops contributes to cognitive and motor deficits in pediatric cerebellar brain tumor survivors. We used a cerebellar white matter atlas and hypothesized that lesion symptom mapping may reveal the critical lesions of cerebellar tracts.

METHODS

We examined 31 long-term survivors of pediatric posterior fossa tumors (13 pilocytic astrocytoma, 18 medulloblastoma). Patients underwent neuronal imaging, examination for ataxia, fine motor and cognitive function, planning abilities, and executive function. Individual consolidated cerebellar lesions were drawn manually onto patients' individual MRI and normalized into Montreal Neurologic Institute (MNI) space for further analysis with voxel-based lesion symptom mapping.

RESULTS

Lesion symptom mapping linked deficits of motor function to the superior cerebellar peduncle (SCP), deep cerebellar nuclei (interposed nucleus (IN), fastigial nucleus (FN), ventromedial dentate nucleus (DN)), and inferior vermis (VIIIa, VIIIb, IX, X). Statistical maps of deficits of intelligence and executive function mapped with minor variations to the same cerebellar structures.

CONCLUSION

We identified lesions to the SCP next to deep cerebellar nuclei as critical for limiting both motor and cognitive function in pediatric cerebellar tumor survivors. Future strategies safeguarding motor and cognitive function will have to identify patients preoperatively at risk for damage to these critical structures and adapt multimodal therapeutic options accordingly.

Raman spectroscopy for medulloblastoma

PURPOSE

The aim of the study is to use Raman spectroscopy to analyze the biochemical composition of medulloblastoma and normal tissues from the safety margin of the CNS and to find specific Raman biomarkers capable of differentiating between tumorous and normal tissues.

METHODS

The tissue samples consisted of medulloblastoma (grade IV) (n = 11). The tissues from the negative margins were used as normal controls. Raman images were generated by a confocal Raman microscope-WITec alpha 300 RSA.

RESULTS

Raman vibrational signatures can predict which tissue has tumorous biochemistry and can identify medulloblastoma. The Raman technique makes use of the fact that tumors contain large amounts of protein and far less lipids (fatty compounds), while healthy tissue is rich in both.

CONCLUSION

The ability of Raman spectroscopy and imaging to detect medulloblastoma tumors fills the niche in diagnostics. These powerful analytical techniques are capable of monitoring tissue morphology and biochemistry. Our results demonstrate that RS can be used to discriminate between normal and medulloblastoma tissues.

Subfrontal recurrence after cerebellar medulloblastoma resection without local relapse: case-based update

OBJECTIVE

This report detailed four cases of tumor recurrence in the subfrontal region after cerebellar medulloblastoma resection without local relapse and explored the causes of recurrence. In addition, a case-based update and insight into the entity is attempted.

METHODS

All four patients received cerebellar medulloblastoma resection and postoperative radiotherapy. They were admitted to our hospital when they were found to have a recurrent tumor in the subfrontal region of the anterior skull base. All four patients received re-resection of the tumor, which was confirmed to be recurrent medulloblastoma by postoperative pathological results.

RESULTS

All patients received local radiotherapy and temozolomide chemotherapy after recurrent tumor resection. They all died due to multiple organ failure resulting from tumor metastasis to other sites or tumor regrowth within 2 years after the second operation.

CONCLUSION

Medulloblastoma metastasize to the subfrontal region and develop a homogenous recurrence is rare. Underdosage of radiation, a gravity-related sanctuary effect, surgical position, and perioperative hydrocephalus management might be factors contributing to this supratentorial meningeal recurrence. A better prevention of tumor recurrence might be achieved by extensive microsurgical tumor resection in the initial operation and by minimizing the need for a permanent V-P shunt in the treatment of perioperative hydrocephalus as well as by administering full-dose radiotherapy to the region of the cribriform plate in the subfrontal area.

Group 3 medulloblastoma in a patient with a GYS2 germline mutation and glycogen storage disease 0a

Glycogen storage disease (GSD) 0a is a rare congenital metabolic disease with symptoms in infancy and childhood caused by biallelic GYS2 germline variants. A predisposition to cancer has not been described yet. We report here a boy with GSD 0a, who developed a malignant brain tumor at the age of 4.5 years. The tumor was classified as a group 3 medulloblastoma, and the patient died from cancer 27 months after initial tumor diagnosis. This case appears interesting as group 3 medulloblastoma is so far not known to arise in hereditary syndromes and the biology of sporadic group 3 medulloblastoma is largely unknown.

A case of multifocal medulloblastoma in an adult patient

Only five cases of multifocal medulloblastoma in the adult have been reported to date. We present a case in a male patient in his 50th decade of life who presented with three extra-axial lesions associated with a parenchymatous lesion of the right middle cerebellar peduncle. Sputum sample examination revealed larvae compatible with strongyloides stercoralis, which was our main differential diagnosis. Histological and immunohistochemical studies revealed the existence of a desmoplastic medulloblastoma.

Imaging Biomarkers for Adult Medulloblastomas: Genetic Entities May Be Identified by Their MR Imaging Radiophenotype

BACKGROUND AND PURPOSE

The occurrence of medulloblastomas in adults is rare; nevertheless, these tumors can be subdivided into genetic and histologic entities each having distinct prognoses. This study aimed to identify MR imaging biomarkers to classify these entities and to uncover differences in MR imaging biomarkers identified in pediatric medulloblastomas.

MATERIALS AND METHODS

Eligible preoperative MRIs from 28 patients (11 women; 22-53 years of age) of the Multicenter Pilot-study for the Therapy of Medulloblastoma of Adults (NOA-7) cohort were assessed by 3 experienced neuroradiologists. Lesions and perifocal edema were volumetrized and multiparametrically evaluated for classic morphologic characteristics, location, hydrocephalus, and Chang criteria. To identify MR imaging biomarkers, we correlated genetic entities sonic hedgehog (SHH) TP53 wild type, wingless (WNT), and non-WNT/non-SHH medulloblastomas (in adults, Group 4), and histologic entities were correlated with the imaging criteria. These MR imaging biomarkers were compared with corresponding data from a pediatric study.

RESULTS

There were 19 SHH TP53 wild type (69%), 4 WNT-activated (14%), and 5 Group 4 (17%) medulloblastomas. Six potential MR imaging biomarkers were identified, 3 of which, hydrocephalus (P = .03), intraventricular macrometastases (P = .02), and hemorrhage (P = .04), when combined, could identify WNT medulloblastoma with 100% sensitivity and 88.3% specificity (95% CI, 39.8%-100.0% and 62.6%-95.3%). WNT-activated nuclear β-catenin accumulating medulloblastomas were smaller than the other entities (95% CI, 5.2-22.3 cm³ versus 35.1-47.6 cm³; P = .03). Hemorrhage was exclusively present in non-WNT/non-SHH medulloblastomas (P = .04; n = 2/5). MR imaging biomarkers were all discordant from those identified in the pediatric cohort. Desmoplastic/nodular medulloblastomas were more rarely in contact with the fourth ventricle (4/15 versus 7/13; P = .04).

CONCLUSIONS

MR imaging biomarkers can help distinguish histologic and genetic medulloblastoma entities in adults and appear to be different from those identified in children.

Imaging mass spectrometry identifies prognostic ganglioside species in rodent intracranial transplants of glioma and medulloblastoma

Matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (MALDI-MSI) allows us to investigate the distribution of lipid molecules within tissues. We used MALDI-MSI to identify prognostic gangliosides in tissue sections of rat intracranial allografts of rat glioma and mouse intracranial xenografts of human medulloblastoma. In the healthy adult rodent brain, GM1 and GD1 were the main types of glycolipids. Both gangliosides were absent in both intracranial transplants. The ganglioside GM3 was not present in the healthy adult brain but was highly expressed in rat glioma allografts. In combination with tandem mass spectrometry GM3 (d18:1/C24:0) was identified as the most abundant ganglioside species in the glioma allotransplant. By contrast, mouse xenografts of human medulloblastoma were characterized by prominent expression of the ganglioside GM2 (d18:0/C18:0). Together, these data demonstrate that tissue-based MALDI-MSI of gangliosides is able to discriminate between different brain tumors and may be a useful clinical tool for their classification and grading.

Use of Digital Whole Slide Imaging in Dermatopathology

Digital whole slide imaging (WSI) is an emerging technology for pathology interpretation, with specific challenges for dermatopathology, yet little is known about pathologists' practice patterns or perceptions regarding WSI for interpretation of melanocytic lesions. A national sample of pathologists (N = 207) was recruited from 864 invited pathologists from ten US states (CA, CT, HI, IA, KY, LA, NJ, NM, UT, and WA). Pathologists who had interpreted melanocytic lesions in the past year were surveyed in this cross-sectional study. The survey included questions on pathologists' experience, WSI practice patterns and perceptions using a 6-point Likert scale. Agreement was summarized with descriptive statistics to characterize pathologists' use and perceptions of WSI. The majority of participating pathologists were between 40 and 59 years of age (62%) and not affiliated with an academic medical center (71%). Use of WSI was seen more often among dermatopathologists and participants affiliated with an academic medical center. Experience with WSI was reported by 41%, with the most common type of use being for education and testing (CME, board exams, and teaching in general, 71%), and clinical use at tumor boards and conferences (44%). Most respondents (77%) agreed that accurate diagnoses can be made with this technology, and 59% agreed that benefits of WSI outweigh concerns. However, 78% of pathologists reported that digital slides are too slow for routine clinical interpretation. The respondents were equally split as to whether they would like to adopt WSI (49%) or not (51%). The majority of pathologists who interpret melanocytic lesions do not use WSI, but among pathologists who do, use is largely for CME, licensure/board exams, and teaching. Positive perceptions regarding WSI slightly outweigh negative perceptions. Understanding practice patterns with WSI as dissemination advances may facilitate concordance of perceptions with adoption of the technology.

[Value of diffusion-weighted imaging, 1H-magnetic resonance spectroscopy and 3D whole-brain arterial spin labeling in the diagnosis of medulloblastoma]

OBJECTIVE

To explore the value of diffusion-weighted imaging (DWI), ¹H-magnetic resonance spectroscopy (1H-MRS) and 3D whole-brain arterial spin labeling (3D ASL) in the diagnosis of medulloblastoma in the posterior cranial fossa.

METHODS

The magnetic resonance imaging (MRI) findings of 16 patients with pathologically confirmed medulloblastoma in the posterior cranial fossa were analyzed retrospectively. All the patients were examined with plane and enhanced brain MRI scans; 5 patients also underwent examinations with DWI, 12 with MRS, and 5 with 3D ASL.

RESULTS

Medulloblastomas were found in the vermis and the fourth ventricle in 9 cases, in the cerebellar hemisphere in 5 cases, and in the cerebellopontine angle in 1 case; in 1 case multiple lesions were detected. The tumors showed iso-intense or slightly hypo-intense signals on T₁WI, and iso-intense or hyper-intense signals on T₂WI and FLAIR. The lesions showed high signals in DWI and low signals in ADC. Intra-lesion cysts were common (n=12), and calcification and bleeding were rarely seen. Mild patchy enhancement (n=6) or significant enhancement (n=10) was seen after contrast agent administration. Obstructive hydrocephalus was found in 12 cases and the subarachnoid space was involved in 3 cases. In all the 12 patients receiving MRS examination, high Cho and low NAA were found with significantly increased Cho/Cr (≥3.5) and Cho/NAA (≥4.0) ratios; Tau peak was seen in 8 cases, and Lip peak was found in 4 cases. All the 5 patients receiving 3D ASL examination showed decreased cerebral blood flow (CBF).

CONCLUSION

The characteristic features of medulloblastomas in DWI, MRS and 3D ASL offer assistance to the diagnosis of atypical medulloblastoma.

Apparent diffusion coefficient mapping in medulloblastoma predicts non-infiltrative surgical planes

INTRODUCTION

An appropriate surgical approach for posterior fossa lesions is to start tumor removal from areas with a defined plane to where tumor is infiltrating the brainstem or peduncles. This surgical approach minimizes risk of damage to eloquent areas. Although magnetic resonance imaging (MRI) is the current standard preoperative imaging obtained for diagnosis and surgical planning of pediatric posterior fossa tumors, it offers limited information on the infiltrative planes between tumor and normal structures in patients with medulloblastomas. Because medulloblastomas demonstrate diffusion restriction on apparent diffusion coefficient map (ADC map) sequences, we investigated the role of ADC map in predicting infiltrative and non-infiltrative planes along the brain stem and/or cerebellar peduncles by medulloblastomas prior to surgery.

METHODS

Thirty-four pediatric patients with pathologically confirmed medulloblastomas underwent surgical resection at our facility from 2004 to 2012. An experienced pediatric neuroradiologist reviewed the brain MRIs/ADC map, assessing the planes between the tumor and cerebellar peduncles/brain stem. An independent evaluator documented surgical findings from operative reports for comparison to the radiographic findings. The radiographic findings were statistically compared to the documented intraoperative findings to determine predictive value of the test in identifying tumor infiltration of the brain stem cerebellar peduncles.

RESULTS

Twenty-six patients had preoperative ADC mapping completed and thereby, met inclusion criteria. Mean age at time of surgery was 8.3 ± 4.6 years. Positive predictive value of ADC maps to predict tumor invasion of the brain stem and cerebellar peduncles ranged from 69 to 88 %; negative predictive values ranged from 70 to 89 %. Sensitivity approached 93 % while specificity approached 78 %.

CONCLUSIONS

ADC maps are valuable in predicting the infiltrative and non-infiltrative planes along the tumor and brain stem interface in medulloblastomas. Inclusion and evaluation of ADC maps in preoperative evaluation can assist in surgical resection planning in patients with medulloblastoma.

Posterior reversible encephalopathy syndrome (PRES): a rare condition after resection of posterior fossa tumors: two new cases and review of the literature

INTRODUCTION

In 1996, Hinchey and colleagues coined the term "Posterior reversible encephalopathy syndrome" (PRES) to describe a condition seen in patients with acute neurological symptoms and reversible subcortical vasogenic edema predominantly involving parieto-occipital areas demonstrated in brain MRI. The occurrence of this phenomenon after surgical resection of CNS tumors is typically linked to pediatric cases.

MATERIAL AND METHODS

Two new cases of PRES after posterior fossa surgery are reported. A thorough review of the literature is carried out with the purpose of updating and summarizing the main features regarding PRES in similar cases. Seven cases of PRES after resection of a posterior fossa tumor have been hitherto reported (4 patients were <20 years old). There is another pediatric case described after a ventriculoperitoneal shunting procedure in a patient with fourth ventricle ependymoma. Two resected tumors were ependymomas, 2 hemangiopericytomas in one patient, 1 pilocyticastrocytoma, 1 vestibular schwannoma, and 1 of the reported cases did not describe the final pathology diagnosis.

CASE REPORTS

We present 2 new cases of PRES after surgical resection of a posterior fossa tumor (medulloblastoma in case 1 and ependymoma in case 2) in pediatric patients. Case 1 developed delayed seizures and altered mental status(10 days after surgical resection) after receiving treatment with bromocriptine for cerebellar mutism. Case 2 presented with generalized seizures and altered mental status within the first 48 postoperative hours followed by right hemiparesis. Both patients fully recovered and returned to neurological baseline status. A thorough review of the literature was carried out with the purpose of updating and summarizing the main features regarding PRES in similar cases.

CONCLUSIONS

We report 2 new pediatric cases of posterior reversible encephalopathy syndrome (PRES) that developed after surgical resection of a posterior fossa tumor. Appropriate management includes supportive measures, antihypertensive agents, and antiepileptic drugs, if needed. Full recovery is the most likely outcome in line with previous articles.

Magnetic resonance imaging features of cerebellar vermis medulloblastoma in an adult canine patient

A seven-year-old, not-castrated male, Airedale Terrier presented with a history of ataxia and intention tremor of the head of three-week duration. Neurologic examination demonstrated severe hypermetria, intention tremor of the head and a bilateral menace response deficit. Magnetic resonance imaging revealed a well demarcated cerebellar vermis mass, hypointense on T1-weighted images, hyperintense on T2-weighted images, with multiple small foci of high signal similar to that of CSF. Foci dispersed in the mass creating a speckled appearance. Homogeneous faint, wispy post-contrast enhancement of the mass was noted; as a result the tumor became isointense to gray matter and was not clearly evident in post contrast images. The histopathological diagnosis of the excised tumor was cerebellar medulloblastoma.

Sudden death due to medulloblastoma: a case report

PURPOSE

Medulloblastoma is one of the notorious CNS malignancies for subtle and atypical clinical presentations, causing rapid neurological deterioration and death, especially in pediatric patients. The delay in diagnosis leads to painful remorse, conflicts, and lawsuits for parents and medical staff.

CASE REPORT

We report a 2 year old girl with initial presentation of febrile pyuria. Soon after admission, a generalized clonic-tonic seizure attacked to her and led to an impression of febrile convulsion. However, an unusual postical slowness of pupils to light stimulation propelled a further investigation. A contrast enhanced brain computer tomography (CT) unexpectedly showed a mass occupied the fourth ventricle resulting in obstructive hydrocephalus and compressed adjacent brain stem and cerebellum. The disease rapidly progressed and she died 18 hours after an emergent decompression with extraventricular drainage (EVD) installation. Cytology of cerebrospinal fluid proved medulloblastoma.

CONCLUSION

This case report highlights the importance of clinical suspicion, such as a trivial but unusual presentation, a lagged pupil response to light stimulation. A brain CT scan should be done to rule out any possibility of an organic lesion. Close monitor is required in order to catch and treat medulloblastoma early. However, once discovered, the cancer has spread.

Hedgehog-mediated regulation of PPARγ controls metabolic patterns in neural precursors and shh-driven medulloblastoma

Sonic hedgehog (Shh) signaling is critical during development and its aberration is common across the spectrum of human malignancies. In the cerebellum, excessive activity of the Shh signaling pathway is associated with the devastating pediatric brain tumor medulloblastoma. We previously demonstrated that exaggerated de novo lipid synthesis is a hallmark of Shh-driven medulloblastoma and that hedgehog signaling inactivates the Rb/E2F tumor suppressor complex to promote lipogenesis. Indeed, such Shh-mediated metabolic reprogramming fuels tumor progression, in an E2F1- and FASN-dependent manner. Here, we show that the nutrient sensor PPARγ is a key component of the Shh metabolic network, particularly its regulation of glycolysis. Our data show that in primary cerebellar granule neural precursors (CGNPs), proposed medulloblastoma cells-of-origin, Shh stimulation elicits a marked induction of PPARγ alongside major glycolytic markers. This is also documented in the actively proliferating Shh-responsive CGNPs in the developing cerebellum, and PPARγ expression is strikingly elevated in Shh-driven medulloblastoma in vivo. Importantly, pharmacological blockade of PPARγ and/or Rb inactivation inhibits CGNP proliferation, drives medulloblastoma cell death and extends survival of medulloblastoma-bearing animals in vivo. This coupling of mitogenic Shh signaling to a major nutrient sensor and metabolic transcriptional regulator define a novel mechanism through which Shh signaling engages the nutrient sensing machinery in brain cancer, controls the cell cycle, and regulates the glycolytic index. This also reveals a dominant role of Shh in the etiology of glucose metabolism in medulloblastoma and underscores the function of the Shh → E2F1 → PPARγ axis in altering substrate utilization patterns in brain cancers in favor of tumor growth. These findings emphasize the value of PPARγ downstream of Shh as a global therapeutic target in hedgehog-dependent and/or Rb-inactivated tumors.

111In-pentetreotide scintigraphy in medulloblastoma: a comparison with magnetic resonance imaging

Medulloblastoma (MB) is a primitive neuroectodermal tumour constituting a grade IV brain malignancy. Early and correct detection of recurrence or metastasis is desirable for follow-up of patients in this entity. Frequent expression of somatostatin receptors by MB lesions facilitates functional tumour imaging by somatostatin receptor scintigraphy (SRS). To investigate the value of SRS in the follow-up of MB, the results of ten consecutive patients (seven children and three adults) undergoing additional imaging with 111In-pentetreotide were reviewed. Four, 24 and 48 h p.i. planar and whole body images as well as a SPECT study at 4 h p.i. were acquired after intravenous injection of 109 +/- 35 MBq 111In-pentetreotide (Octreoscan). SRS yielded 11 positive and ten negative imaging results, compared to 17 positive and four negative in magnetic resonance imaging (MRI). The lesion-by-lesion analysis with a total of 44 lesions revealed a sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 42%, 83%, 94%, 18% for SRS and 89.5%, 50%, 92%, 43% for MRI. Based on a per-patient analysis, considering the patient as to be either tumour-free or tumour-positive by one imaging modality, the following values for sensitivity, specificity, PPV and NPV were obtained: 61%, 100%, 100%, 30% for SRS and 94%, 67%, 94%, 67% for MRI. MRI remains the first step imaging technique in medulloblastoma patients before and after surgery and during the follow-up providing the highest sensitivity. However, to improve specificity and contribute to correct diagnosis in MB 111In-pentetreotide scintigraphy should be considered as a confirmatory second step imaging tool, especially in case of equivocal MRI results. Moreover, a positive SRS scan might serve as a reference before and after somatostatin receptor targeted radiotherapy.

Metabolism of orthotopic mouse brain tumor models

We used magnetic resonance spectroscopy to determine whether orthotopic mouse brain tumors grown as xenografts in immunocompromised mice either from human brain tumor cells implanted immediately after surgery or from cultured human tumor lines show metabolic profiles comparable to those of the original tumors. Using a 7 T scanner, spectra were acquired from mice with a human atypical teratoid/rhabdoid tumor (AT/RT) either implanted directly from the surgical specimen or first grown in culture, directly implanted choroid plexus carcinoma (CPC), and two medulloblastoma cell lines. The results were compared with spectra from these same tumors or tumor types in patients and with controls. Metabolic variability of tumors from a single cell line was also evaluated using the medulloblastoma lines. The main metabolic features of human tumors were qualitatively replicated in xenografts. AT/RTs in mice exhibited choline, creatine, and myo-inositol levels comparable to those observed in the patient. As in patients, choline was prominent in experimental CPC. Tumors from a single cell line were comparable. Significant correlations were found with key metabolites in humans and mice; however, differences including lower lipids in the implanted AT/RTs than in patient spectra and taurine observed in all animal spectra were also noted. The causes of these dissimilarities warrant further investigation.

[Brain tumors in childhood]

Central nervous system (CNS) tumors are the most common solid neoplasms in childhood and the second most common malignancies after leukemia in the pediatric age group. Supratentorial tumors are more common in children younger than 2 years old and in adolescents, whereas in patients between 2 and 12 years of age brain tumors originating in the posterior fossa dominate. This implies a relationship between the type of tumor, its location and the age of the patient, which has to be considered in differential diagnoses. Medulloblastoma represents the most common malignant brain tumor in childhood. In the posterior fossa medulloblastomas are approximately as frequent as astrocytomas. Supratentorial astrocytomas are by far the main tumor type. In this report some typical CNS neoplasms in children are discussed and their neuroradiological features are demonstrated.

Temozolomide treatment of an adult with a relapsing medulloblastoma

Temozolomide is an oral cytotoxic agent that has demonstrated its interest in high grade glioma tumors. This drug can be used either concomitantly with radiotherapy or as chemotherapy. The prognosis of relapsing medulloblastoma is poor and treatment is often difficult, especially after radiotherapy. Here, we report the use of temozolomide in an adult presenting relapsing medulloblastoma. An initial partial response was observed for this previously heavily treated patient. This observation suggests this drug may be useful in medulloblastoma, either as conventional chemotherapy or for use together with radiotherapy.

[Imaging of pediatric brain tumors using somatostatin analogue 111Ih-DTPA-D-Phe1-octreotide]

Malignant solid tumors and leukemias are the second most common causes of death in childhood. The most frequent pediatric solid tumors are brain tumors. Brain tumors, especially medulloblastoma should be treated by surgery, irradiation and chemotherapy. However, chemotherapy has only moderate effect. Pediatric brain tumors, especially medulloblastomas, express somatostatin receptors. The aim of this study was the investigation of the expression of somatostatin receptors in pediatric brain tumors for diagnostic and therapeutic purpose. Fifty-six scintigraphic imagings (111In-DTPA-D-Phe1-octreotide) made in 45 children treated with brain tumor at the Unit of Oncology of the 2nd Department of Pediatrics, Semmelweis University. The diagnosis was medulloblastoma in 21 cases (46.7%). MRI scans have been performed parallel with the Octreoscan images. Octreoscan images were positive in 27 of 56 (48.2%) cases. The 27 positive Octreoscan images consisted of 16 medulloblastomas, 4 ependymomas, 4 astrocytomas and 3 glioblastomas. In 37 (66.1%) cases the results of Octreoscans were the same as those of the MRI scans. However, in 19 scans (33.9%) the outcome was different. Octreoscan imaging is not suitable for differential diagnosis in pediatric brain tumors, including medulloblastomas. Isotopes specifically binding to the somatostatin receptors (111In-DTPA-D-Phe1-octreotide) can be applied in medulloblastomas for diagnosis and follow-up treatment. In Octreoscan-positive tumors the Octreoscan images establish the opportunity to somatostatin analogue and/or specifically targeted radiation therapies.

Intensity-Modulated Radiotherapy for Craniospinal Irradiation: Target Volume Considerations, Dose Constraints, and Competing Risks

PURPOSE

To report the results of an analysis of dose received to tissues and organs outside the target volume, in the setting of spinal axis irradiation for the treatment of medulloblastoma, using three treatment techniques.

METHODS AND MATERIALS

Treatment plans (total dose, 23.4 Gy) for a standard two-dimensional (2D) technique, a three-dimensional (3D) technique using a 3D imaging-based target volume, and an intensity-modulated radiotherapy (IMRT) technique, were compared for 3 patients in terms of dose-volume statistics for target coverage, as well as organ at risk (OAR) and overall tissue sparing.

RESULTS

Planning target volume coverage and dose homogeneity was superior for the IMRT plans for V(95%) (IMRT, 100%; 3D, 96%; 2D, 98%) and V(107%) (IMRT, 3%; 3D, 38%; 2D, 37%). In terms of OAR sparing, the IMRT plan was better for all organs and whole-body contour when comparing V(10Gy), V(15Gy), and V(20Gy). The 3D plan was superior for V(5Gy) and below. For the heart and liver in particular, the IMRT plans provided considerable sparing in terms of V(10Gy) and above. In terms of the integral dose, the IMRT plans were superior for liver (IMRT, 21.9 J; 3D, 28.6 J; 2D, 38.6 J) and heart (IMRT, 9 J; 3D, 14.1J; 2D, 19.4 J), the 3D plan for the body contour (IMRT, 349 J; 3D, 337 J; 2D, 555 J).

CONCLUSIONS

Intensity-modulated radiotherapy is a valid treatment option for spinal axis irradiation. We have shown that IMRT results in sparing of organs at risk without a significant increase in integral dose.

Craniospinal irradiation using a forward planned segmented field technique

Craniospinal irradiation is technically demanding due to the complex shape of the planning target volume (PTV). Radiotherapy treatment techniques have evolved over time as imaging and radiotherapy treatment technology have improved. However, most are variations on a class solution utilizing a prone patient position with two shaped lateral cranial portals and a matched posterior spinal portal with moving junctions. Major areas of difficulty remain with the accurate definition of the PTV and achieving a homogeneous dose within it, especially at the junctions. We describe a three-dimensionally (3D) planned craniospinal radiation technique that permits rapid image acquisition with reduced localization time, simplified spinal PTV definition and standardized cranial PTV definition. Improved dose homogeneity within the PTV is achieved by use of a segmented "field-in-field" technique (forward planned intensity-modulated radiotherapy (IMRT)) in place of customized compensators. This has negated the requirement for constructing physical compensators. Autosequencing for field delivery enables the junction to be "moved" during a single fraction and reduces the overall treatment time, an important consideration when treating very young patients.

[Diagnosis and micro-neurosurgery for the fourth cerebral ventricle tumors]

OBJECTIVE

To investigate the diagnostic method and analyze the result of microneurosurgical treatment for tumors of the fourth cerebral ventricle.

METHODS

Tumor of the fourth ventricle was clinically diagnosed in 86 patients basing on the preliminary assessment of symptom and CT or MRI findings. Of these 86 patients treated with micro-neurosurgery, the tumors in 62 were totally removed, subtotally in 19, and partially in 5. Forty-two patients received postoperative radiotherapy.

RESULTS

Three patients died postoperatively within ten days, and symptoms in 83 were improved after treatment. The average survival period was over 3 years. The pathology included 32 medulloblastomas, 23 ependymoma, 15 astrocytoma, 10 hemangiblastomas, 2 choroid plexus papillomas, and 4 epidermoid cysts.

CONCLUSION

Medulloblastoma, astrocytoma and hemangiblastoma are suggested to be removed totally whenever technically possible according to the site, character and volume of the tumor. For ependymoma, if close to the brain stem, is recommended to be subtotally removed. Postoperative radiotherapy may be beneficial for malignant types.

Mouse models of brain tumors and their applications in preclinical trials

Primary brain tumors, including gliomas and medulloblastomas, often represent the most devastating and difficult-to-treat tumors, and are thought to arise from glial cells and/or their precursors or the external granule cell layer, respectively. The majority of genetic alterations characteristic of the human brain tumors are thought to occur in genes encoding proteins involved in signal transduction or cell cycle regulation. Accurate recapitulation of these genetic alterations using genetically engineered mouse models allows for in vivo modeling of brain tumors with similar histopathology, etiology, and biology. These mouse models, in turn, increase our understanding of brain tumor initiation, formation, progression, and metastasis, providing an experimental system to discover novel therapeutic targets and test various therapeutic agents.