The 2016 World Health Organization Classification of tumours of the Central Nervous System: what the paediatric neuroradiologist needs to know

The recently published 2016 World Health Organization (WHO) classification of tumours of the Central Nervous System (CNS) introduces a number of significant changes from the previous edition. Based on an improved understanding of the genetic and molecular basis of tumorigenesis there has been a shift towards defining tumours by means of these characteristics in addition to their histological features, thus providing an integrated diagnosis. In this article, we will provide a concise overview of the salient changes in the 2016 WHO classification of tumours of the CNS that are of relevance to the paediatric neuroradiologist when it comes to day-to-day reporting

Surveillance imaging of grade 1 astrocytomas in children: can duration and frequency of follow-up imaging and the use of contrast agents be reduced?

Purpose: The optimum strategy for the surveillance of low-grade gliomas in children has not been established, and there is concern about the use of gadolinium-based contrast agents (GBCAs), particularly in children, due to their deposition in the brain. The number of surveillance scans and the use of GBCAs in surveillance of low-risk tumours should ideally be limited. We aimed to investigate the consistency and utility of our surveillance imaging and also determine to what extent the use of GBCAs contributed to decisions to escalate treatment in children with grade 1 astrocytomas. / Methods: This was a retrospective single-centre study at a tertiary paediatric hospital. All children with a new diagnosis of a non-syndromic World Health Organization (WHO) grade 1 astrocytoma between 2007 and 2013 were included, with surveillance imaging up to December 2018 included in analysis. The intervals of surveillance imaging were recorded, and imaging and electronic health records were examined for decisions related to treatment escalation. / Results: Eighty-eight patients had 690 surveillance scans in the study period. Thirty-one patients had recurrence or progression leading to treatment escalation, 30 of whom were identified on surveillance imaging. The use of GBCAs did not appear to contribute to multidisciplinary team (MDT) decisions in the majority of cases. / Conclusion: Surveillance imaging could be reduced in number and duration for completely resected cerebellar tumours. MDT decisions were rarely made on the basis of post-contrast imaging, and GBCA administration could therefore potentially be restricted in the setting of surveillance of grade 1 astrocytomas in children

Narrative review of epilepsy: getting the most out of your neuroimaging

Neuroimaging represents an important step in the evaluation of pediatric epilepsy. The crucial role of brain imaging in the diagnosis, follow-up and presurgical assessment of patients with epilepsy is noted and has to be familiar to all neuroradiologists and trainees approaching pediatric brain imaging. Morphological qualitative imaging shows the majority of cerebral lesions/alterations underlying focal epilepsy and can highlight some features which are useful in the differential diagnosis of the different types of epilepsy. Recent advances in MRI acquisitions including diffusion-weighted imaging (DWI), post-acquisition image processing techniques, and quantification of imaging data are increasing the accuracy of lesion detection during the last decades. Functional MRI (fMRI) can be really useful and helps to identify cortical eloquent areas that are essential for language, motor function, and memory, and diffusion tensor imaging (DTI) can reveal white matter tracts that are vital for these functions, thus reducing the risk of epilepsy surgery causing new morbidities. Also positron emission tomography (PET), single photon emission computed tomography (SPECT), simultaneous electroencephalogram (EEG) and fMRI, and electrical and magnetic source imaging can be used to assess the exact localization of epileptic foci and help in the design of intracranial EEG recording strategies. The main role of these “hybrid” techniques is to obtain quantitative and qualitative informations, a necessary step to evaluate and demonstrate the complex relationship between abnormal structural and functional data and to manage a “patient-tailored” surgical approach in epileptic patients

Dynamic MRI lesion evolution in paediatric MOG-Ab associated disease (MOGAD)

INTRODUCTION: Myelin oligodendrocyte glycoprotein (MOG) antibodies are associated clinically with either a monophasic or relapsing disease course in both children and adults. There are few studies studying lesion evolution in children with myelin oligodendrocyte glycoprotein antibody associated disorder (MOGAD). AIM: The aim of this study was to examine MRI lesion evolution over time in a large single-centre paediatric MOGAD cohort. METHODS: We retrospectively identified patients with MOGAD from a tertiary paediatric neurosciences centre (Great Ormond Street Hospital) between 2001 to 2022. RESULTS: A total of 363 MRI scans from 59 included patients were available for analysis. Median age at presentation was 4 yrs (IQR 4-9), 32 (54.2%) were female and 34 (57.6%) were of non-white ethnicities. Twenty-seven children (45.8%) had a monophasic illness and 32 (54.2%) had a relapsing disease course. In the relapsing MOGAD group, median number of relapses was 4 (range 2-30). Initial presentation was ADEM in 27(46%), ON in 18 (31%) ADEM-ON in 4 (7%), ADEM-TM in 6 (10%) TM in 2 (3%) ADEM-TM-ON in 1 (2%) and ON-Brainstem syndrome in 1 (2%). There was no difference in demographics or clinical presentation between monophasic and relapsing groups. Fifteen patients (25.4%) had gadolinium enhancement on initial attack MRI. Seven out of 32 (21.9%) relapsing patients had persistent enhancement on follow-up MRI scans. One patient with a clinical transverse myelitis at presentation was MRI negative. New asymptomatic lesions following first clinical event were seen in 5/27 (18.5%) monophasic patients and 8/32 (25%) relapsing patients. During follow-up interval scanning,38 out of 59 have had follow up neuroimaging after their first attack whereas15/32 had relapsed before having a follow up MRI. Complete lesion resolution was reported in 9/38 (23.6%) (8 monophasic, 1 relapsing) following 1st acute attack, 3/32 (9.3%) after 2nd acute attack, and 1/32 (3.1%) following 3rd acute attack and 0/32 following 4th acute attack. Partial resolution of MRI lesions was seen in 7/20 (35%) monophasic patients and 7/32 (21.8%) relapsing patients at follow-up scans. CONCLUSIONS: Demyelinating lesions in paediatric MOGAD are dynamic and timing of MRI scanning may influence CNS region involvement. Unlike in multiple sclerosis, a significant number of MOGAD patients will have complete lesion resolution at first follow-up, although the ability to repair is reduced following multiple relapses

Arterial Spin-Labeling Perfusion Metrics in Pediatric Posterior Fossa Tumor Surgery

BACKGROUND AND PURPOSE: Pediatric posterior fossa tumors often present with hydrocephalus; postoperatively, up to 25% of patients develop cerebellar mutism syndrome. Arterial spin-labeling is a noninvasive means of quantifying CBF and bolus arrival time. The aim of this study was to investigate how changes in perfusion metrics in children with posterior fossa tumors are modulated by cerebellar mutism syndrome and hydrocephalus requiring pre-resection CSF diversion. MATERIALS AND METHODS: Forty-four patients were prospectively scanned at 3 time points (preoperatively, postoperatively, and at 3-month follow-up) with single- and multi-inflow time arterial spin-labeling sequences. Regional analyses of CBF and bolus arrival time were conducted using coregistered anatomic parcellations. ANOVA and multivariable, linear mixed-effects modeling analysis approaches were used. The study was registered at clinicaltrials.gov (NCT03471026). RESULTS: CBF increased after tumor resection and at follow-up scanning (P = .045). Bolus arrival time decreased after tumor resection and at follow-up scanning (P = .018). Bolus arrival time was prolonged (P = .058) following the midline approach, compared with cerebellar hemispheric surgical approaches to posterior fossa tumors. Multivariable linear mixed-effects modeling showed that regional perfusion changes were more pronounced in the 6 children who presented with symptomatic obstructive hydrocephalus requiring pre-resection CSF diversion, with hydrocephalus lowering the baseline mean CBF by 20.5 (standard error, 6.27) mL/100g/min. Children diagnosed with cerebellar mutism syndrome (8/44, 18.2%) had significantly higher CBF at follow-up imaging than those who were not (P = .040), but no differences in pre- or postoperative perfusion parameters were seen. CONCLUSIONS: Multi-inflow time arterial spin-labeling shows promise as a noninvasive tool to evaluate cerebral perfusion in the setting of pediatric obstructive hydrocephalus and demonstrates increased CBF following resolution of cerebellar mutism syndrome

Magnetic resonance imaging findings in children with Parry-Romberg syndrome and en coup de sabre

BACKGROUND: The aim of this study was to: (i) describe the abnormalities seen on brain imaging in a group of children with en coup de sabre (EDCS) with/without Parry-Romberg syndrome (PRS); and (ii) identify clinical predictors of brain imaging abnormalities. METHODS: This was a single centre (Great Ormond Street Hospital, London) retrospective case series of patients with ECDS/PRS seen from 2000 to 2018. We identified patients with cutaneous manifestations consistent with the clinical descriptions of ECDS/PRS. Presenting clinical, laboratory, and radiological brain findings are described. Results are expressed as medians and ranges or frequencies and percentages. Fisher's exact test was used to identify clinical associations with magnetic resonance imaging (MRI) abnormalities. RESULTS: Fourteen patients were studied: 6 males and 8 females; median age 14 years (range 3-20). We observed neuroimaging abnormalities in 2/6 ECDS and 5/8 ECDS/PRS patients. White matter signal abnormality, dystrophic calcification, leptomeningeal enhancement, and sulcal crowding were the typical findings on brain imaging. A total of 50% of patients had no MRI abnormality despite some of these patients having neurological symptoms. The presence of seizures was significantly associated with ipsilateral enhanced white matter signalling on MRI (p < 0.05). CONCLUSIONS: In summary, we observed several distinct radiographic patterns associated with ECDS/PRS. Seizure disorder was strongly associated with the presence of ipsilateral enhanced white matter signalling. Improved neuroimaging techniques that combine morphological with functional imaging may improve the detection rate of brain involvement in children with ECDS/PRS in the future