Pediatric Neuro-oncology Research Articles

68Ga-NOTA-Aca-BBN(7-14) PET imaging of GRPR in children with optic pathway glioma.

Optic pathway glioma (OPG) is a rare neoplasm that arises predominantly during childhood. Its location in a sensitive region involving the optic pathways, onset in young patients and controversial therapy choice make the management of OPG a challenge in paediatric neuro-oncology. In this study we assessed gastrin-releasing peptide receptor (GRPR)-targeted positron emission tomography (PET) imaging in children with OPG, and the application of a PET/MRI imaging-guided surgery navigation platform. Eight children (five boys, mean age 8.81years, range 5-14years) with suspicion of optic pathway glioma on MRI were recruited. Written informed consent was obtained from all patients and legal guardians. Brain PET/CT or PET/MRI acquisitions were performed 30min after intravenous injection of 1.85MBq/kg body weight of 68Ga-NOTA-Aca-BBN(7-14). Four patients also underwent 18F-FDG brain PET/CT for comparison. All patients underwent surgical resection within 1week. All 11 lesions (100%) in the eight patients showed prominent 68Ga-NOTA-Aca-BBN(7-14) uptake with excellent contrast in relation to surrounding normal brain tissue. Tumour-to-background ratios (SUVmax and SUVmean) were significantly higher for 68Ga-NOTA-Aca-BBN(7-14) than for 18F-FDG (28.4 ± 5.59 vs. 0.47 ± 0.11 and 18.3 ± 4.99 vs. 0.35 ± 0.07, respectively). Fusion images for tumour delineation were obtained in all patients using the PET/MRI navigation platform. All lesions were pathologically confirmed as OPGs with positive GRPR expression, and 75% were pilocytic astrocytoma WHO grade I and 25% were diffuse astrocytoma WHO grade II. There was a positive correlation between the SUV of 68Ga-NOTA-Aca-BBN(7-14) and the expression level of GRPR (r2 = 0.56, P < 0.01, for SUVmax; r2 = 0.47, P < 0.05, for SUVmean). This prospective study showed the feasibility of 68Ga-NOTA-Aca-BBN(7-14) PET in children with OPG for tumour detection and localization. 68Ga-NOTA-Aca-BBN(7-14) PET/MRI may be helpful for assisting surgery planning in OPG patients with severe symptoms, GRPR-targeted PET has the potential to provide imaging guidance for further GRPR-targeted therapy in patients with OPG.

Abstract 3667: The Pediatric Brain Tumor Atlas - Transforming the landscape of research

Abstract The Pediatric Brain Tumor Atlas (PBTA) is a cloud-based, cross-platform, and data-rich collaborative effort to accelerate discoveries for therapeutic intervention in children diagnosed with brain tumors. Pediatric brain tumors are the leading cause of disease-related death in children and despite advances in therapy, morbidity and mortality rates remain poor. There have been large scale efforts to genomically profile these cancers in the past, however public access to the resulting datasets are limited at best. In contrast, the PBTA, created as a multi-center effort by Children’s Brain Tumor Tissue Consortium (CBTTC) and Pacific Pediatric Neuro-Oncology Consortium (PNOC), has a goal of characterizing over 1,600 pediatric brain tumor samples and making the data publicly available to cancer researchers world-wide. PBTA comprises comprehensive clinical data in addition to whole exome sequencing, whole genome sequencing (WGS), RNA sequencing (RNASeq), miRNA sequencing, and proteomics. To address the need to inform novel discovery and clinical implementation of genomic approaches for diagnostic/therapeutic purposes, PBTA utilizes a cloud-based scientific environment, the CAVATICA portal. CAVATICA provides near real-time integration, dissemination, processing, and sharing of associated PetaByte-sized data by leveraging Amazon Web Services and powerful genomic workflows. It also enables dbGaP approved users to access TCGA and other datasets hosted by NCI’s Cancer Genomics’ Cloud, allowing for cross-disease studies. While CAVATICA manages raw sequencing data, processed annotations and biospecimen querying is enabled for PBTA via PedcBioPortal, a data visualization/analysis application further integrating additional public and deposited datasets. PBTA data can further be accessed via the KidsFirst platform, which integrates both CAVATICA and PedcBioPortal, and allows for querying of cancer and non-cancer genomic data for subsequent analytics, visualization, and discovery. The 1st dataset release of PBTA occurred on September 10th, 2018. In this release there are over 30 different types of pediatric brain tumors representing over 1,000 subjects. This data is available on CAVATICA, KidsFirst, and PedcBioPortal and users can seamlessly move between applications. Data types include those for matched tumor/normal samples, such as WGS, RNASeq, proteomics, longitudinal clinical data, imaging data (MRIs and radiology reports), histology slide images, and pathology reports. CBTTC/PNOC promote real time data release with no embargo period, allowing PBTA to have is up-to-date data releases with no embargo. The combination of cloud-based analytic platforms such as KidsFirst/CAVATICA/PedcBioPortal with data from both genomics and clinical practice serves to define a new paradigm for pediatric cancer research and collaborative discovery. Citation Format: Yuankun Zhu, Yiran Guo, Allison P. Heath, Pichai Raman, Elizabeth Appert, Jennifer Mason, Bo Zhang, Karthik Kalletla, Miguel A. Brown, Natasha Singh, Bailey K. Farrow, Parimala Killada, Meen Chul Kim, Alex Felmeister, Mateusz P. Koptyra, Sabine Mueller, Michael Prados, Jena V. Lilly, Rishi Lulla, Adam C. Resnick, Javad Nazarian, Phillip B. Storm, Angela J. Waanders. The Pediatric Brain Tumor Atlas - Transforming the landscape of research [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3667.

Herausforderungen und Zukunftsperspektiven in der Neuroonkologie

Neuro-oncology is ayoung and emerging discipline. An interdisciplinary mindset and concerted actions in specialized expert teams are required to meet the challenges, not only in clinical patient care but also in research activities. Aclose communication network between clinician scientists, medical scientists and data scientists is required to ensure that emerging data from basic, translational and clinical research can be used for improving the sometimes extremely limited and prognostically unsatisfactory treatment options. The continuously developing spectrum of tasks in neuro-oncology includes the classical fields of primary and metastatic tumors of the central nervous system and neurological complications from cancer therapies. It also includes challenges of transition of patients with adisease onset in childhood from pediatric to adult neuro-oncology. This is particularly relevant because the treatment options and the prognosis of primary brain tumors in childhood have improved tremendously. Thus, a close cooperation between pediatric and adult neuro-oncology is necessary to ensure a seamless transition. All these considerations lead to specific challenges for specialized centers of excellence to ensure an innovative, competitive and sustainable framework for modern neuro-oncology.

Molecular profiling and targeted therapy in pediatric gliomas: review and consensus recommendations.

As the field of neuro-oncology makes headway in uncovering the key oncogenic drivers in pediatric glioma, the role of precision diagnostics and therapies continues to rapidly evolve with important implications for the standard of care for clinical management of these patients. Four studies at major academic centers were published in the last year outlining the clinically integrated molecular profiling and targeting of pediatric brain tumors; all 4 demonstrated the feasibility and utility of incorporating sequencing into the care of children with brain tumors, in particular for children and young adults with glioma. Based on synthesis of the data from these studies and others, we provide consensus recommendations for the integration of precision diagnostics and therapeutics into the practice of pediatric neuro-oncology. Our primary consensus recommendation is that next-generation sequencing should be routinely included in the workup of most pediatric gliomas.

Early Postoperative 18F-FET PET/MRI for Pediatric Brain and Spinal Cord Tumors.

Complete resection is the treatment of choice for most pediatric brain tumors, but early postoperative MRI for detection of residual tumor may be misleading because of MRI signal changes caused by the operation. PET imaging with amino acid tracers in adults increases the diagnostic accuracy for brain tumors, but the literature in pediatric neurooncology is limited. A hybrid PET/MRI system is highly beneficial in children, reducing the number of scanning procedures, and this is to our knowledge the first larger study using PET/MRI in pediatric neurooncology. We evaluated if additional postoperative 18F-fluoro-ethyl-tyrosine (18F-FET) PET in children and adolescents would improve diagnostic accuracy for the detection of residual tumor as compared with MRI alone and would assist clinical management. Methods: Twenty-two patients (7 male; mean age, 9.5 y; range, 0-19 y) were included prospectively and consecutively in the study and had 27 early postoperative 18F-FET PET exams performed preferentially in a hybrid PET/MRI system (NCT03402425). Results: Using follow-up (93%) or reoperation (7%) as the reference standard, PET combined with MRI discriminated tumor from treatment effects with a lesion-based sensitivity/specificity/accuracy (95% confidence intervals) of 0.73 (0.50-1.00)/1.00 (0.74-1.00)/0.87 (0.73-1.00) compared with MRI alone: 0.80 (0.57-1.00)/0.75 (0.53-0.94)/0.77 (0.65-0.90); that is, the specificity for PET/MRI was 1.00 as compared with 0.75 for MRI alone (P = 0.13). In 11 of 27 cases (41%), results from the 18F-FET PET scans added relevant clinical information, including one scan that directly influenced clinical management because an additional residual tumor site was identified. 18F-FET uptake in reactive changes was frequent (52%), but correct interpretation was possible in all cases. Conclusion: The high specificity for detecting residual tumor suggests that supplementary 18F-FET PET is relevant in cases where reoperation for residual tumor is considered.

Neurooncology Research in Nigeria: Great Untapped Potential

Nigeria has the largest population in Africa and has suboptimal access to neurooncology care. It has been estimated that there is approximately 1 neurosurgeon for every 2.4 million people in the country, with only few of these trained in the neurooncology subspecialty and no dedicated medical or radiation neurooncologists. There is a paucity of information on the field of neurooncology in Nigeria. This manuscript aims to provide an overview of the current state of neurooncology literature in Nigeria. A systematic literature review was performed, using Google Scholar, PubMed, and African Journals Online, to search for articles related to neurooncology in Nigeria, from 1963-2018. Articles were reviewed and categorized. Sixty-three relevant articles were identified. They comprised original research in basic science (N= 1), clinical science (N= 59), and reviews (N= 3). Retrospective case series were the most common type of publication. Categorizing according to histology, articles focused on meningioma (N= 12), pituitary tumors (N= 10), glioma (N= 7), central nervous system metastases (N= 6), multiple histologic types (N= 25), and other types of tumors (N= 3). Eight pediatric neurooncology publications were among these. Two manuscripts, focusing on surgical subjects, specifically addressed issues on neurooncology clinical practice in Nigeria. Of the total manuscripts, 26 were published in Nigerian-based journals and 37 in journals outside Nigeria. The majority of the journals were low-impact factor journals. An increasing number of publications over time was noted. There is a small but growing amount of scholarly literature on neurooncology from Nigeria. However, there continues to be room for growth in neurooncology research output. With Nigeria's large patient population, there is potential to learn and add to the academic literature. Although there are logistical obstacles to both patient care and research in neurooncology in Nigeria, there is promise for favorable advancement.

The Latin American Brain Tumor Board teleconference: results of a web-based survey to evaluate participant experience utilizing this resource.

The Latin American Brain Tumor Board (LATB) is a weekly teleconference connecting pediatric neuro-oncologists from referral centers in high-income countries with pediatric subspecialists from 20 Latin American countries since 2013. This survey explored the participants' experience utilizing this resource. A cross-sectional electronic questionnaire was distributed to 159 participants through email and Cure4Kids. Ninety-five respondents (60%) from all the participating countries completed the survey. Sixty-one reported frequent-attendance (≥ 1 per month), 23 reported infrequent-attendance (< 1 per month), and 11 never participated. The most frequently reported attendance-barriers were the subspecialist's workload (64%), the timing of the teleconference (38%), and Internet connectivity problems (29%). Subspecialist's workload was more frequently reported as a barrier compared with other barriers, in both the frequent- and infrequent-attendance groups (p < 0.05), with the exception of the timing of the meeting in the infrequent-attendance group. More than 80% of attendees found the frequency and duration of the teleconference were sufficient. Utilizing Spanish as the primary language was reported to enhance the recommendations by 93% of the attendees. Moreover, 84% reported that the recommendations (almost) always fit the local circumstances. Furthermore, 99% of attendees found the teleconference provided a continuing medical education opportunity. Finally, 96% of attendees (almost) always found that the provided recommendations helped to improve the outcomes/quality of life of the patients. The LATB teleconference provided a valuable tool for the management of pediatric brain tumors in Latin America as it provided a feasible and easy to access continued medical education opportunity for the participants.

Use of hyperbaric oxygen therapy in pediatric neuro-oncology: a single institutional experience.

Hyperbaric oxygen therapy (HBOT) has been utilized as adjunctive treatment of CNS tumors and for radiation necrosis (RN) with reported success. The safety and efficacy in pediatric patients is less understood. Seven patients (ages 10-23 years, six females) were treated with HBOT (3-60 sessions) for either RN (n = 5) or tumor-associated edema (n = 2). Tumor diagnosis included low-grade glioma (n = 4, two with neurofibromatosis type 1), meningioma (n = 1), medulloblastoma (n = 1) and secondary high grade glioma (n = 1). Prior therapies included: surgery (n = 4), chemotherapy (n = 4) and radiation (N = 5: four focal, one craniospinal). Three underwent biopsy: one confirming RN, one high-grade glioma, and one low-grade glioma. Patients were assessed for clinical and radiographic changes post HBOT. Median time to clinical and radiographic presentation was 8.5months (range 6 months-11years) in those who had prior radiation. Clinical improvement after HBOT (median: 40 sessions) was observed in four of seven patients. Symptoms were stable in two and worsened in one patient. Radiographic improvement was seen in four patients; three had radiographic disease progression. In the subgroup treated for presumed and biopsy-confirmed RN (n = 5), four of five (80%) had clinical and radiographic improvement. There were no long-term adverse events due to HBOT. HBOT is safe and well-tolerated in pediatric and young adult patients with CNS tumors. Clinical and radiographic improvements were observed in over half of patients. Clinical trials are needed to establish safety and efficacy of HBOT as adjunct therapy in pediatric CNS tumors.

Radiotherapy Advances in Pediatric Neuro-Oncology.

Radiation therapy (RT) represents an integral component in the treatment of many pediatric brain tumors. Multiple advances have emerged within pediatric radiation oncology that aim to optimize the therapeutic ratio—improving disease control while limiting RT-related toxicity. These include innovations in treatment planning with magnetic resonance imaging (MRI) simulation, as well as increasingly sophisticated radiation delivery techniques. Advanced RT techniques, including photon-based RT such as intensity-modulated RT (IMRT) and volumetric-modulated arc therapy (VMAT), as well as particle beam therapy and stereotactic RT, have afforded an array of options to dramatically reduce radiation exposure of uninvolved normal tissues while treating target volumes. Along with advances in image guidance of radiation treatments, novel RT approaches are being implemented in ongoing and future prospective clinical trials. As the era of molecular risk stratification unfolds, personalization of radiation dose, target, and technique holds the promise to meaningfully improve outcomes for pediatric neuro-oncology patients.

Pediatric Brain Tumor Genetics: What Radiologists Need to Know.

Brain tumors are the most common solid tumors in the pediatric population. Pediatric neuro-oncology has changed tremendously during the past decade owing to ongoing genomic advances. The diagnosis, prognosis, and treatment of pediatric brain tumors are now highly reliant on the genetic profile and histopathologic features of the tumor rather than the histopathologic features alone, which previously were the reference standard. The clinical information expected to be gleaned from radiologic interpretations also has evolved. Imaging is now expected to not only lead to a relevant short differential diagnosis but in certain instances also aid in predicting the specific tumor and subtype and possibly the prognosis. These processes fall under the umbrella of radiogenomics. Therefore, to continue to actively participate in patient care and/or radiogenomic research, it is important that radiologists have a basic understanding of the molecular mechanisms of common pediatric central nervous system tumors. The genetic features of pediatric low-grade gliomas, high-grade gliomas, medulloblastomas, and ependymomas are reviewed; differences between pediatric and adult gliomas are highlighted; and the critical oncogenic pathways of each tumor group are described. The role of the mitogen-activated protein kinase pathway in pediatric low-grade gliomas and of histone mutations as epigenetic regulators in pediatric high-grade gliomas is emphasized. In addition, the oncogenic drivers responsible for medulloblastoma, the classification of ependymomas, and the associated imaging correlations and clinical implications are discussed. ©RSNA, 2018.

Haemostatic material (Surgicel®) mimicking residual tumour: magnetic resonance imaging findings in operated pediatric neuro-oncology cases.

Surgical resection is the first line treatment in the majority of pediatric brain tumors. Even in cases when total resection is not possible, a subtotal debulking is used to reduce mass effect and to provide tissue for histological and molecular diagnosis, necessary to guide oncologic therapies, to assess risk stratification and to predict prognosis (1-3).

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

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

Building a Neuro-Oncology Program and Epidemiological Profiling of Pediatric Brain Tumors in a Tertiary Cancer Care Center in India

Background: Treatment of childhood brain tumours requires coordinated efforts by multiple specialities - neurosurgery, neuroradiology, neuropathology, oncology, and radiotherapy. The outcome is worse in developing countries compared to developed countries because of deficiencies in proper registry, failure of timely diagnosis, lack of availability and co-ordination of multiple specialists required for comprehensive management and high abandonment rates.Method: The pediatric neuro-oncology program was initiated in collaboration with the neighbouring neurosurgery institution as a step towards improving care for pediatric brain tumor patients in our hospital. Epidemiology, treatment and followup of brain tumours in children aged 1-14 years attending the pediatric oncology department were studied. Patients received multimodality treatment with surgery, radiotherapy and chemotherapy by specialists in both centres. The study period was from January 2008 to December 2012.Results: There were 375 pediatric brain tumour patients during the study period. 166 patients (44.2%) had supratentorial tumors and 209 (55.73%) had infratentorial tumors. 42.6% of tumours were high-grade and 53.6% were low grade. The commonest histopathological tumour type was astrocytoma (48.8%) followed by medullobastoma (24.5%). 287 (76.5%) patients underwent surgery, 216 (57.6%) patients received radiotherapy, 97 (25.8%) patients received chemotherapy and 94 (25%) required follow-up only. Patient follow-up rates improved from 37.2% to 82.6% and treatment abandonment decreased from 35.8% to 14.8% over these years.Conclusions: Impact of the pediatric neuro-oncology program in our hospital has made it possible to provide comprehensive multidisciplinary treatment in a co-ordinated manner, describe the epidemiology of pediatric brain tumors, reduce treatment abandonment, and improve the follow-up of pediatric brain tumour patients.

Abstracts from the 18th International Symposium on Pediatric Neuro-Oncology (ISPNO 2018) June 30 – July 3, 2018 Hyatt Regency Hotel Denver, Colorado, USA

Abstracts from the 18th International Symposium on Pediatric Neuro-Oncology (ISPNO 2018) June 30 – July 3, 2018 Hyatt Regency Hotel Denver, Colorado, USA

Malignant Brain Tumours in Children : Present and Future Perspectives.

In contrast to many of the malignant tumors that occur in the central nervous system in adults, the management, responses to therapy, and future perspectives of children with malignant lesions of the brain hold considerable promise. Within the past 5 years, remarkable progress has been made with our understanding of the basic biology of the molecular genetics of several pediatric malignant brain tumors including medulloblastoma, ependymoma, atypical teratoid rhabdoid tumour, and high grade glioma/diffuse intrinsic pontine glioma. The recent literature in pediatric neuro-oncology was reviewed, and a summary of the major findings are presented. Meaningful sub-classifications of these tumors have arisen, placing children into discrete categories of disease with requirements for targeted therapy. While the mainstay of therapy these past 30 years has been a combination of central nervous system irradiation and conventional chemotherapy, now with the advent of high resolution genetic mapping, targeted therapies have emerged, and less emphasis is being placed on craniospinal irradiation. In this article, the present and future perspective of pediatric brain malignancy are reviewed in detail. The progress that has been made offers significant hope for the future for patients with these tumours.

Response to Harreld re: "Response assessment in medulloblastoma and leptomeningeal seeding tumors: recommendations from the Response Assessment in Pediatric Neuro-Oncology Committee".

Response to Harreld re: "Response assessment in medulloblastoma and leptomeningeal seeding tumors: recommendations from the Response Assessment in Pediatric Neuro-Oncology Committee".

Comment on "Response assessment in medulloblastoma and leptomeningeal seeding tumors: recommendations from the Response Assessment in Pediatric Neuro-Oncology Committee".

Comment on "Response assessment in medulloblastoma and leptomeningeal seeding tumors: recommendations from the Response Assessment in Pediatric Neuro-Oncology Committee".

Precision Medicine in Pediatric Neurooncology: A Review.

Central nervous system tumors are the leading cause of cancer related death in children. Despite much progress in the field of pediatric neurooncology, modern combination treatment regimens often result in significant late effects, such as neurocognitive deficits, endocrine dysfunction, secondary malignancies, and a host of other chronic health problems. Precision medicine strategies applied to pediatric neurooncology target specific characteristics of individual patients’ tumors to achieve maximal killing of neoplastic cells while minimizing unwanted adverse effects. Here, we review emerging trends and the current literature that have guided the development of new molecularly based classification schemas, promising diagnostic techniques, targeted therapies, and delivery platforms for the treatment of pediatric central nervous system tumors.

Development of the CNS TAP tool for the selection of precision medicine therapies in neuro-oncology.

The number of targeted therapies utilized in precision medicine are rapidly increasing. Neuro-oncology offers a unique challenge due to the varying blood brain barrier (BBB) penetration of each agent. Neuro-oncologists face a difficult task weighing the growing number of potential targeted therapies and their likelihood of BBB penetration. We developed the CNS TAP Working Group and performed an extensive literature review for the evidence-based creation of the CNS TAP tool, which was retrospectively validated by analyzing brain tumor patients who underwent therapy targeted based on genomic results from an academic sequencing study (MiOncoseq, n = 17) or private molecular profiling (Foundation One, n = 7). The CNS TAP tool scores relevant targeted agents by applying multiple variables (i.e., pre-clinical data, clinical data, BBB permeability) to patient specific genomic information and clinical trial availability. In the Michigan cohort, the CNS TAP tool predicted the selected agent 85.7% of the time. The CNS TAP tool predicted the agent independently selected by pediatric neuro-oncologists in the Colorado cohort 50% of the time. Patients with recurrent brain tumors treated with agents predicted by the CNS TAP tool demonstrated a median progression-free survival of 4 months and four patients with recurrent high-grade glioma maintained ongoing partial responses of at least 6 months. The CNS TAP tool is a formalized algorithm to assist clinicians select the optimal targeted therapy for neuro-oncology patients. The CNS TAP tool has relatively high concordance with selected therapies and clinical outcomes in patients receiving targeted therapy in this heterogeneous retrospective cohort were promising.

NIMG-42. EXPERIENCE WITH 18F-FET PET/MRI FOR CNS-TUMORS IN CHILDREN AND ADOLESCENTS

Positron Emission Tomography (PET) with 18F-fluoro-ethyltyrosine (18F-FET) improves diagnostic accuracy in adult patients with gliomas but the literature in pediatric neuro-oncology is still scarce. We aimed 1) to collect a material of various pediatric brain tumors 2) to determine sensitivity and specificity for tumor using 18F-FET PET versus MRI alone 3) to test the clinical impact of the scans. Eighty patients with primary pediatric CNS-tumors was included and a total of 121 hybrid 18F-FET PET/MRI or PET/CT scans have been performed. Clinical impact was assessed as minor (change of diagnosis) or major (change of treatment plan). Minor impact was seen in 28% of all scans and major impact in 9%. In the 27 cases, when a PET scan had beforehand been regarded clinically indicated, 38% showed minor impact and 35% showed major impact. A high uptake was seen in pilocytic astrocytoma and in high grade gliomas, while lower uptake was seen in e.g. AT/RT (atypical teratoid/rhabdoid tumor), ependymoma, germinomas. No increased uptake was seen in e.g. non-contrast enhancing low grade glioma. In 24 early postoperative 18F-FET PET scans conducted primarily within 72 hours after surgery, minor impact was seen in 42% and major impact in 4% of cases. Based on a consensus reading for residual tumor of follow-up scans (up to 24 months), we found the following lesion-based sensitivity/specificity/accuracy for diagnosing residual tumor: MRI alone: 80%/64%/72%. PET/MRI: 73%/100%/86%. The addition of 18F-FET PET to MRI for imaging of pediatric CNS-tumors has a major impact on the clinical management in 9% of all scans and in 35% of the clinically indicated scans. The addition of 18F-FET PET for early postoperative imaging seems to increase the specificity for residual tumor and should be considered when radical surgery is of high priority, especially if MRI is equivocal.