Examining the associations between microglia genetic capacity, early life exposures and white matter development at the level of the individual

There are inter-individual differences in susceptibility to the influence of early life experiences for which the underlying neurobiological mechanisms are poorly understood. Microglia play a role in environmental surveillance and may influence individual susceptibility to environmental factors. As an index of neurodevelopment, we estimated individual slopes of mean white matter fractional anisotropy (WM-FA) across three time-points (age 4.5, 6.0, and 7.5 years) for 351 participants. Individual variation in microglia reactivity was derived from an expression-based polygenic score(ePGS) comprised of Single Nucleotide Polymorphisms (SNPs) functionally related to the expression of microglia-enriched genes.A higher ePGS denotes an increased genetic capacity for the expression of microglia-related genes, and thus may confer a greater capacity to respond to the early environment and to influence brain development. We hypothesized that this ePGS would associate with the WM-FA index of neurodevelopment and moderate the influence of early environmental factors.Our findings show sex dependency, where a significant association between WM-FA and microglia ePGS was only obtained for females.We then examined associations with perinatal factors known to decrease (optimal birth outcomes and familial conditions) or increase (systemic inflammation) the risk for later mental health problems.In females, individuals with high microglia ePGS showed a negative association between systemic inflammation and WM-FA and a positive association between more advantageous environmental conditions and WM-FA. The microglia ePGS in females thus accounted for variations in the influence of the quality of the early environment on WM-FA.Finally, WM-FA slopes mediated the association of microglia ePGS with interpersonal problems and social hostility in females. Our findings suggest the genetic capacity for microglia function as a potential factor underlying differential susceptibility to early life exposuresthrough influences on neurodevelopment.

Microglial function interacts with the environment to affect sex-specific depression risk

There is a two-fold higher incidence of depression in females compared to men with recent studies suggesting a role for microglia in conferring this sex-dependent depression risk. In this study we investigated the nature of this relation. Using GWAS enrichment, gene-set enrichment analysis and Mendelian randomization, we found minimal evidence for a direct relation between genes functionally related to microglia and sex-dependent genetic risk for depression. We then used expression quantitative trait loci and single nucleus RNA-sequencing resources to generate polygenic scores (PGS) representative of individual variation in microglial function in the adult (UK Biobank; N = 54753-72682) and fetal (ALSPAC; N = 1452) periods. The adult microglial PGS moderated the association between BMI (UK Biobank; beta = 0.001, 95 %CI 0.0009 to 0.003, P = 7.74E-6) and financial insecurity (UK Biobank; beta = 0.001, 95 %CI 0.005 to 0.015, P = 2E-4) with depressive symptoms in females. The fetal microglia PGS moderated the association between maternal prenatal depressive symptoms and offspring depressive symptoms at 24 years in females (ALSPAC; beta = 0.04, 95 %CI 0.004 to 0.07, P = 0.03). We found no evidence for an interaction between the microglial PGS and depression risk factors in males. Our results illustrate a role for microglial function in the conferral of sex-dependent depression risk following exposure to a depression risk factor.

In-vivo whole-cortex marker of excitation-inhibition ratio indexes cortical maturation and cognitive ability in youth

A balanced excitation-inhibition ratio (E/I ratio) is critical for healthy brain function. Normative development of cortex-wide E/I ratio remains unknown. Here we non-invasively estimate a putative marker of whole-cortex E/I ratio by fitting a large-scale biophysically-plausible circuit model to resting-state functional MRI (fMRI) data. We first confirm that our model generates realistic brain dynamics in the Human Connectome Project. Next, we show that the estimated E/I ratio marker is sensitive to the GABA-agonist benzodiazepine alprazolam during fMRI. Alprazolam-induced E/I changes are spatially consistent with positron emission tomography measurement of benzodiazepine receptor density. We then investigate the relationship between the E/I ratio marker and neurodevelopment. We find that the E/I ratio marker declines heterogeneously across the cerebral cortex during youth, with the greatest reduction occurring in sensorimotor systems relative to association systems. Importantly, among children with the same chronological age, a lower E/I ratio marker (especially in association cortex) is linked to better cognitive performance. This result is replicated across North American (8.2 to 23.0 years old) and Asian (7.2 to 7.9 years old) cohorts, suggesting that a more mature E/I ratio indexes improved cognition during normative development. Overall, our findings open the door to studying how disrupted E/I trajectories may lead to cognitive dysfunction in psychopathology that emerges during youth.

Neonatal Nucleus Accumbens Microstructure Modulates Individual Susceptibility to Preconception Maternal Stress in Relation to Externalizing Behaviors

OBJECTIVE

Maternal stress influences in utero brain development and is a modifiable risk factor for offspring psychopathologies. Reward circuitry dysfunction underlies various internalizing and externalizing psychopathologies. This study examined (1) the association between maternal stress and microstructural characteristics of the neonatal nucleus accumbens (NAcc), a major node of the reward circuitry, and (2) whether neonatal NAcc microstructure modulates individual susceptibility to maternal stress in relation to childhood behavioral problems.

METHOD

K-means longitudinal cluster analysis was performed to determine trajectories of maternal stress measures (Perceived Stress Scale [PSS], hair cortisol) from preconception to the third trimester. Neonatal NAcc microstructural measures (orientation density index [ODI] and intracellular volume fraction [ICVF]) were compared across trajectories. We then examined the interaction between maternal stress and neonatal NAcc microstructure on child internalizing and externalizing behaviors, assessed between ages 3 and 4 years.

RESULTS

Two trajectories of maternal stress magnitude ("low"/"high") were identified for both PSS (n = 287) and hair cortisol (n = 336). Right neonatal NAcc ODI (rNAcc-ODI) was significantly lower in "low" relative to "high" PSS trajectories (n = 77, p = .04). PSS at preconception had the strongest association with rNAcc-ODI (r = 0.293, p = .029). No differences in NAcc microstructure were found between hair cortisol trajectories. A significant interaction between preconception PSS and rNAcc-ODI on externalizing behavior was observed (n = 47, p = .047).

CONCLUSION

Our study showed that the preconception period contributes to in utero NAcc development, and that NAcc microstructure modulates individual susceptibility to preconception maternal stress in relation to externalizing problems.

Screen time, brain network development and socio-emotional competence in childhood: moderation of associations by parent-child reading

BACKGROUND

Screen time in infancy is linked to changes in social-emotional development but the pathway underlying this association remains unknown. We aim to provide mechanistic insights into this association using brain network topology and to examine the potential role of parent-child reading in mitigating the effects of screen time.

METHODS

We examined the association of screen time on brain network topology using linear regression analysis and tested if the network topology mediated the association between screen time and later socio-emotional competence. Lastly, we tested if parent-child reading time was a moderator of the link between screen time and brain network topology.

RESULTS

Infant screen time was significantly associated with the emotion processing-cognitive control network integration (p = 0.005). This network integration also significantly mediated the association between screen time and both measures of socio-emotional competence (BRIEF-2 Emotion Regulation Index, p = 0.04; SEARS total score, p = 0.04). Parent-child reading time significantly moderated the association between screen time and emotion processing-cognitive control network integration (β = -0.640, p = 0.005).

CONCLUSION

Our study identified emotion processing-cognitive control network integration as a plausible biological pathway linking screen time in infancy and later socio-emotional competence. We also provided novel evidence for the role of parent-child reading in moderating the association between screen time and topological brain restructuring in early childhood.

Variations in Cortical Functional Gradients Relate to Dimensions of Psychopathology in Preschool Children

OBJECTIVE

It is unclear how the functional brain hierarchy is organized in preschool-aged children, and whether alterations in the brain organization are linked to mental health in this age group. Here, we assessed whether preschool-aged children exhibit a brain organizational structure similar to that of older children, how this structure might change over time, and whether it might reflect mental health.

METHOD

This study derived functional gradients using diffusion embedding from resting state functional magnetic resonance imaging data of 4.5-year-old children (N = 100, 42 male participants) and 6.0-year-old children (N = 133, 62 male participants) from the longitudinal Growing Up in Singapore Towards healthy Outcomes (GUSTO) cohort. We then conducted partial least-squares correlation analyses to identify the association between the impairment ratings of different mental disorders and network gradient values.

RESULTS

The main organizing axis of functional connectivity (ie, principal gradient) separated the visual and somatomotor regions (ie, unimodal) in preschool-aged children, whereas the second axis delineated the unimodal-transmodal gradient. This pattern of organization was stable from 4.5 to 6 years of age. The second gradient separating the high- and low-order networks exhibited a diverging pattern across mental health severity, differentiating dimensions related to attention-deficit/hyperactivity disorder and phobic disorders.

CONCLUSION

This study characterized, for the first time, the functional brain hierarchy in preschool-aged children. A divergence in functional gradient pattern across different disease dimensions was found, highlighting how perturbations in functional brain organization can relate to the severity of different mental health disorders.

An algorithmic clinicoradiological approach to paediatric cranial vault lesions: distinguishing normal variants from pathologies

Lesions of the paediatric cranial vault are diverse both in their presentation and aetiology. As such, they pose a diagnostic challenge to the paediatric neurosurgeon and neuroradiologist. In this article, we delineate the spectrum of paediatric calvarial pathology into four distinct groups: (1) lytic lesion(s); (2) focal sclerotic lesion(s); (3) diffuse cranial vault sclerosis; and (4) abnormal shape of the cranial vault. It is our aim that this more pragmatic, algorithmic approach may mitigate diagnostic uncertainty and aid the more accurate diagnosis of paediatric calvarial lesions.

Functional activity of the caudate mediates the relation between early childhood microstructural variations and elevated metabolic syndrome scores

BACKGROUND

Metabolic syndrome score in children assesses the risk of developing cardiovascular disease in future. We aim to probe the role of the caudate in relation to the metabolic syndrome score. Furthermore, using both functional and structural neuroimaging, we aim to examine the interplay between functional and structural measures.

METHODS

A longitudinal birth cohort study with functional and structural neuroimaging data obtained at 4.5, 6.0 and 7.5 years and metabolic syndrome scores at 8.0 years was used. Pearson correlation and linear regression was used to test for correlation fractional anisotropy (FA) and fractional amplitude of low frequency fluctuations (fALFF) of the caudate with metabolic syndrome scores. Mediation analysis was used to test if later brain measures mediated the relation between earlier brain measures and metabolic syndrome scores. Inhibitory control was also tested as a mediator of the relation between caudate brain measures and metabolic syndrome scores.

RESULTS

FA at 4.5 years and fALFF at 7.5 years of the left caudate was significantly correlated with metabolic syndrome scores. Post-hoc mediation analysis showed that fALFF at 7.5 years fully mediated the relation between FA at 4.5 years and metabolic syndrome scores. Inhibitory control was significantly correlated with fALFF at 7.5 years, but did not mediate the relation between fALFF at 7.5 years and metabolic syndrome scores.

CONCLUSIONS

We found that variations in caudate microstructure at 4.5 years predict later variation in functional activity at 7.5 years. This later variation in functional activity fully mediates the relation between microstructural changes in early childhood and metabolic syndrome scores at 8.0 years.

Homotopic local-global parcellation of the human cerebral cortex from resting-state functional connectivity

Resting-state fMRI is commonly used to derive brain parcellations, which are widely used for dimensionality reduction and interpreting human neuroscience studies. We previously developed a model that integrates local and global approaches for estimating areal-level cortical parcellations. The resulting local-global parcellations are often referred to as the Schaefer parcellations. However, the lack of homotopic correspondence between left and right Schaefer parcels has limited their use for brain lateralization studies. Here, we extend our previous model to derive homotopic areal-level parcellations. Using resting-fMRI and task-fMRI across diverse scanners, acquisition protocols, preprocessing and demographics, we show that the resulting homotopic parcellations are as homogeneous as the Schaefer parcellations, while being more homogeneous than five publicly available parcellations. Furthermore, weaker correlations between homotopic parcels are associated with greater lateralization in resting network organization, as well as lateralization in language and motor task activation. Finally, the homotopic parcellations agree with the boundaries of a number of cortical areas estimated from histology and visuotopic fMRI, while capturing sub-areal (e.g., somatotopic and visuotopic) features. Overall, these results suggest that the homotopic local-global parcellations represent neurobiologically meaningful subdivisions of the human cerebral cortex and will be a useful resource for future studies. Multi-resolution parcellations estimated from 1479 participants are publicly available (https://github.com/ThomasYeoLab/CBIG/tree/master/stable_projects/brain_parcellation/Yan2023_homotopic).

Functional connectivity analysis of childhood depressive symptoms

BACKGROUND

Childhood depression is a highly distinct and prevalent condition with an unknown neurobiological basis. We wish to explore the resting state fMRI data in children for potential associations between neural connectivity and childhood depressive symptoms.

METHODS

A longitudinal birth cohort study with neuroimaging data obtained at 4.5, 6.0 and 7.5 years of age and the Children Depression Inventory 2 (CDI) administered between 8.5 and 10.5 years was used. The CDI score was used as the dependent variable and tested for correlation, both simple Pearson and network based statistic, with the functional connectivity values obtained from the resting state fMRI. Cross-validated permutation testing with a general linear model was used to validate that the identified functional connections were indeed implicated in childhood depression.

RESULTS

Ten functional connections and four brain regions (Somatomotor Area B, Temporoparietal Junction, Orbitofrontal Cortex and Insula) were identified as significantly associated with childhood depressive symptoms for girls at 6.0 and 7.5 years. No significant functional connections were found in girls at 4.5 years or for boys at any timepoint. Network based statistic and permutation testing confirmed these findings.

CONCLUSIONS

This study revealed significant sex-dependent associations of neural connectivity and childhood depressive symptoms. The regions identified are implicated in speech/language, social cognition and information integration and suggest unique pathways to childhood depressive symptoms.

DNA methylation-based classification of glioneuronal tumours synergises with histology and radiology to refine accurate molecular stratification

AIMS

Glioneuronal tumours (GNTs) are poorly distinguished by their histology and lack robust diagnostic indicators. Previously, we showed that common GNTs comprise two molecularly distinct groups, correlating poorly with histology. To refine diagnosis, we constructed a methylation-based model for GNT classification, subsequently evaluating standards for molecular stratification by methylation, histology and radiology.

METHODS

We comprehensively analysed methylation, radiology and histology for 83 GNT samples: a training cohort of 49, previously classified into molecularly defined groups by genomic profiles, plus a validation cohort of 34. We identified histological and radiological correlates to molecular classification and constructed a methylation-based support vector machine (SVM) model for prediction. Subsequently, we contrasted methylation, radiological and histological classifications in validation GNTs.

RESULTS

By methylation clustering, all training and 23/34 validation GNTs segregated into two groups, the remaining 11 clustering alongside control cortex. Histological review identified prominent astrocytic/oligodendrocyte-like components, dysplastic neurons and a specific glioneuronal element as discriminators between groups. However, these were present in only a subset of tumours. Radiological review identified location, margin definition, enhancement and T2 FLAIR-rim sign as discriminators. When validation GNTs were classified by SVM, 22/23 classified correctly, comparing favourably against histology and radiology that resolved 17/22 and 15/21, respectively, where data were available for comparison.

CONCLUSIONS

Diagnostic criteria inadequately reflect glioneuronal tumour biology, leaving a proportion unresolvable. In the largest cohort of molecularly defined glioneuronal tumours, we develop molecular, histological and radiological approaches for biologically meaningful classification and demonstrate almost all cases are resolvable, emphasising the importance of an integrated diagnostic approach.

Effects of maternal childhood trauma on child emotional health: maternal mental health and frontoamygdala pathways

BACKGROUND

Experiences of early life adversity pose significant psychological and physical health risks to exposed individuals. Emerging evidence suggests that these health risks can be transmitted across generations; however, the mechanisms underlying the intergenerational impacts of maternal early-life trauma on child health remain unknown.

METHODS

The current study used a prospective longitudinal design to determine the unique and joint contributions of maternal childhood trauma (neglect and abuse) and maternal prenatal and postnatal mental health (anxiety and depressive symptoms) (N = 541) to children's resting frontoamygdala functional connectivity at 6 years (N = 89) and emotional health at 7-8 years, as indexed by parent-reported internalizing problems and child self-reported anxiety and depressive symptoms (N = 268-418).

RESULTS

Greater maternal childhood neglect was indirectly associated with greater internalizing problems serially through a pathway of worse maternal prenatal and postnatal mental health (greater maternal anxiety and depressive symptoms). Worse maternal postnatal mental health was also uniquely associated with more negative child frontoamygdala resting-state functional connectivity, over and above maternal childhood trauma (both neglect and abuse) and prenatal mental health. More negative frontoamygdala functional connectivity was, in turn, associated with poorer child emotional health outcomes.

CONCLUSIONS

Findings from the current study provide support for the existence of intergenerational influences of parental exposure to childhood trauma on childhood risk for psychopathology in the next generation and point to the importance of maternal factors proximal to the second generation (maternal prenatal and postnatal mental health) in determining the intergenerational impact of maternal early experiences.

Structure-function coupling within the reward network in preschool children predicts executive functioning in later childhood

Early differences in reward behavior have been linked to executive functioning development. The nucleus accumbens (NAc) and orbitofrontal cortex (OFC) are activated by reward-related tasks and identified as key nodes of the brain circuit that underlie reward processing. We aimed to investigate the relation between NAc-OFC structural and functional connectivity in preschool children, as well as associations with future reward sensitivity and executive function. We showed that NAc-OFC structural and functional connectivity were not significantly associated in preschool children, but both independently predicted sensitivity to reward in males in a left-lateralized manner. Moreover, significant NAc-OFC structure-function coupling was only found in individuals who performed poorly on executive function tasks in later childhood, but not in the middle- and high-performing groups. As structure-function coupling is proposed to measure functional specialization, this finding suggests premature functional specialization within the reward network, which may impede dynamic communication with other regions, affects executive function development. Our study also highlights the utility of multimodal imaging data integration when studying the effects of reward network functional flexibility in the preschool age, a critical period in brain and executive function development.

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Functional connectivity is not tethered to structural connectivity in preschool age.

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Higher degree of SC-FC coupling reflects lower plasticity in early childhood.

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Gender differences in reward sensitivity were present as early as in preschool age.

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Early reward network SC-FC coupling affects later executive function.

Clinical application of "black bone" imaging in paediatric craniofacial disorders

For decades, CT has been the primary imaging modality for the diagnosis and surveillance of paediatric craniofacial disorders. However, the deleterious effects of ionising radiation in the paediatric population are well established and remain an ongoing concern. This is especially so in the head and neck region, which has relatively poor soft tissue shielding with many radiosensitive organs. The development of "black bone" imaging utilising low flip angles and short echo time (TE) has shown considerable promise in alleviating the use of ionising radiation in many cases of craniofacial disorders. In this review article, we share our experience of utilising "black bone" sequence in children with craniofacial pathologies, ranging from traumatic injuries to craniosynostosis and focal osseous/fibro-osseous lesions such as fibrous dysplasia and Langerhans cell histiocytosis (LCH). A detailed discussion on the technical aspects of "black bone" sequence, including its potential pitfalls and limitations, will also be included.

Dynamic radiation-induced imaging changes more than 20 years following gamma knife surgery

Gamma knife radiosurgery (GKS), a technique which involves delivery of a high dose of radiation to a precisely defined target, has become the predominant treatment option for brain metastases (BM) because of its high effectiveness and relatively minimal toxicity. Herein, we report a case of late-onset radiation-induced edema around an asymptomatic cyst, more than 20 years after salvage GKS, with 27 years of imaging follow-up, allowing the description of the evolutionary trajectory of these relatively rare complications. Our reported case also demonstrated the benign nature of delayed cyst formation (DCF), emphasizing that observation alone is reasonable for asymptomatic patients.

Left lateralization of neonatal caudate microstructure affects emerging language development at 24 months

The complex interaction between brain and behaviour in language disorder is well established. Yet to date, the imaging literature in the language disorder field has continued to pursue heterogeneous and relatively small clinical cross‐sectional samples, with emphasis on cortical structures and volumetric analyses of subcortical brain structures. In our current work, we aimed to go beyond this state of knowledge to focus on the microstructural features of subcortical brain structures (specifically the caudate nucleus) in a large cohort of neonates and study its association with emerging language skills at 24 months. Variations in neonatal brain microstructure could be interpreted as a proxy for in utero brain development. As language development is highly dependent on cognitive function and home literacy environment, we also examined their effect on the caudate–language function relationship utilizing a conditional process model. Our findings suggest that emerging language development at 24 months is influenced by the degree of left lateralization of neonatal caudate microstructure, indexed by diffusion tensor imaging (DTI)‐derived fractional anisotropy (FA). FA is an indirect measure of neuronal and dendritic density within grey matter structures. We also found that the caudate–language function relationship is partially mediated by cognitive function. The conditional indirect effect of left caudate FA on language composite score through cognitive function was only statistically significant at low levels of home literacy score (−1 standard deviation [SD]). The authors proposed that this may be related to ‘compensatory’ development of cognitive skills in less favourable home literacy environments.

CAR T-cell therapy-related neurotoxicity in paediatric acute lymphocytic leukaemia

BACKGROUND

The advent of chimeric antigen receptor (CAR) T-cell therapy has created a paradigm shift in the management of patients with refractory B-cell acute lymphocytic leukaemia (ALL). The aim of this study is to correlate imaging findings of CAR T-cell therapy related neurotoxicity with clinical course and eventual clinical outcome, with the hope that it will bring us a step closer to the identification of potential imaging biomarkers that may allow more accurate prognostication and risk stratification of patients.

PROCEDURE

Our imaging database was queried from January 2018 to April 2020 to identify paediatric patients who fulfil the following criteria: (a) diagnosed with ALL, (b) underwent CAR T-cell therapy, and (c) had magnetic resonance imaging (MRI) brain studies performed before and after CAR T-cell therapy. A total of seven patients were included and all MRI studies were analysed by a paediatric neuroradiologist for the presence of acute neuroimaging findings post CAR T-cell infusion. Acute neuroimaging findings are defined as new imaging findings detected within 28 days of CAR T-cell infusion.

RESULTS

Three out of four patients with acute neuroimaging findings had sustained complete remission for more than 6 months, while all three patients without acute neuroimaging findings had positive minimal residual disease (MRD) within 1 month. Both patients with acute diffuse leptomeningeal enhancement showed clinical improvement within 1-2 days.

CONCLUSIONS

Acute neuroimaging findings may be a potential imaging biomarker for peak neurotoxicity and treatment response, and it is not necessarily associated with poor outcome, as previously reported.

CAR-T Cell Therapy-Related Neurotoxicity in Pediatric Acute Lymphoblastic Leukemia: Spectrum of Imaging Findings

The emergence of CD19-targeted chimeric antigen receptor-T (CAR-T) cell therapy has created a new era in the management of pediatric patients with refractory B-cell malignancies such as B-cell acute lymphoblastic leukemia. Immune effector cell-associated neurotoxicity syndrome (ICANS) is frequently encountered in the postinfusion period of CD19-targeted chimeric antigen receptor-T cell therapy and in some cases may be fatal. Knowledge related to the spectrum of imaging findings of CD19-targeted CAR-T cell therapy-related ICANS is, however, still very much lacking, underscoring the need for continued research in this area. In this review, we hope to provide an overview of current knowledge and provide an in-depth literature review related to this topic. A brief discussion of possible imaging differential diagnoses, specifically in children with acute lymphoblastic leukemia, will also be included. Illustrative cases for each imaging phenotype will be provided to facilitate a better understanding. A greater level of insight of the spectrum of imaging findings related to ICANS will improve patients' management and enhance efforts to safely deliver CAR-T cell immunotherapy. It will also facilitate further studies to derive mechanistic insights of ICANS and potentially assist in the testing and monitoring of therapeutic interventions.

SIR HELMET (Safety In Radiology HEalthcare Localised Metrological EnviromenT): a low-cost negative-pressure isolation barrier for shielding MRI frontline workers from COVID-19 exposure

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Low cost reusable acrylic and silicone rubber barrier shield design.

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Localised negative pressure environment simulating isolation rooms.

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Does not affect MRI image quality even on the most sensitive sequences.

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Additional personal protective equipment for frontline healthcare professionals.

Correction to: Venous pathologies in paediatric neuroradiology: from foetal to adolescent life

The original version of this article unfortunately contained a referencing omission. Figure 11 is reused from the original publication of Figure 10 of Gunny and Lin [1].

Neuroimaging Spectrum of Inherited Neurotransmitter Disorders

Inherited neurotransmitter disorders are rare neurometabolic conditions which encompass genetic disorders of neurotransmitter metabolism or transport. The clinical manifestations of these rare disorders are often nonspecific, ranging from encephalopathies and seizures to movement disorders. As a consequence, neurotransmitter disorders are underrecognized and often misdiagnosed. Accurate and timely diagnosis is, however, of utmost importance, given the availability of therapeutic strategies. A high index of clinical suspicion and familiarity with the neuroimaging phenotypes is therefore crucial. While the imaging features of various neurotransmitter disorders often overlap and are nonspecific, imaging can be helpful in providing useful clues to guide the diagnostic algorithm for uncommon conditions in a neonate presenting with nonspecific neurological symptoms. In this review paper, we aim to bring together current knowledge of neuroimaging phenotypes associated with inherited (primary) disorders of neurotransmitter biosynthesis. Magnetic resonance imaging phenotypes of disorders of monoamine biosynthesis, primary cerebral folate deficiency, disorders of pyridoxine metabolism, disorders of gamma-aminobutyric acid metabolism, nonketotic hyperglycinemia (glycine encephalopathy), disorders of serine biosynthesis, and cerebral creatine deficiency syndrome will be discussed and illustrated with case examples.

A Novel Method of CT Exophthalmometry in Patients With Thyroid Eye Disease

PURPOSE

Conventional computed tomography (CT) exophthalmometry requires an intact lateral orbital wall and is therefore not feasible in patients who have undergone any form of lateral orbital wall surgery where the normal bony landmark may be lost or displaced. The purpose of our study is to validate an alternative method of CT exophthalmometry utilizing the posterior clinoid (PC) process as a new reference point that will allow for reproducible comparison of the anterior-posterior globe position in the preoperative and postoperative settings.

DESIGN

Cohort study.

METHODS

This is a retrospective study of 48 patients with clinically diagnosed thyroid eye disease who had undergone cross-sectional CT imaging in the pre- or postoperative settings. CT exophthalmometry was performed using both the conventional interzygomatic method and our proposed PC process method on all pre- and postoperative CT imaging by two independent observers. Interobserver variability analysis was performed with intraclass correlation coefficient. Correlation and agreement between the two methods were analyzed with Pearson correlation coefficient and linear regression method. All analyses were conducted at 5% level of significance with Stata MP V14.

RESULTS

Interobserver variability analysis showed an intraclass correlation coefficient of >0.9 for both interzygomatic and PC methods. There is good correlation between the two different measurements observed in both the pre- and postoperative groups (r = 0.68 and r = 0.72, respectively, P < 0.001). Linear regression showed good agreement between the two different measurements with most of the points lying within the 95% limits.

CONCLUSIONS

Our new method agrees well with the conventional method and has the added benefit of being able to reliably assess the anterior-posterior globe position in patients who do not have intact lateral orbital walls after decompressive surgery.

Acute hemichorea in a young type 1 diabetic

Purpose/Aim: Acute movement disorder is an uncommon presenting symptom in patients with diabetes mellitus. We report a 20-year-old lady with poorly controlled type 1 diabetes, who presented with acute hemichorea and was found to have two rare diabetes-related central nervous complications of diabetic striatopathy and severe moyamoya disease (MMD).Materials and methods: She was treated with aggressive glycemic control; clonazepam and tetrabenazine as well as aspirin stroke prophylaxis for her MMD with resolution of her chorea 3 months later. She subsequently underwent cerebral revascularization surgery for her MMD.Results: This case highlights the possible differentials of acute chorea in diabetic patients and explores the pathophysiological mechanisms that may underlie both conditions in patients with type 1 diabetes.Conclusion: We recommend performing both magnetic resonance imaging (MRI) and magnetic resonance angiogram (MRA) brain for comprehensive evaluation of diabetic patients with new onset chorea. Prompt and accurate diagnosis is crucial as it guides prognostication and treatment strategies.

Anaplastic Oligodendroglioma with Transdural Extension

Oligodendrogliomas, the third most common primary gliomas, have a strict molecular definition, characterized by the combined presence of isocitrate dehydrogenase mutation and 1p19q codeletion. Herein, we describe an extremely unusual case of molecularly defined anaplastic oligodendroglioma with transdural extension into the frontal and ethmoid sinuses, without prior neurosurgical intervention or radiotherapy. The molecular profile of the tumor is also provided. To the best of our knowledge, this has never been reported before. Most of the previously reported glial tumors with transdural extension were cases of histologically proven glioblastomas and gliosarcomas, typically seen in the context of prior neurosurgical intervention and/or radiotherapy. This case adds to the limited literature on oligodendrogliomas with transdural extension. Further studies are necessary to elucidate the relationship between the incidence of transdural extension and molecular subtypes of oligodendrogliomas.

"Restricted Diffusion" within the Splenium of the Corpus Callosum: A Potential Pitfall in Young Infants on 3T Imaging and Marker of Normal Myelin Maturation

PURPOSE

To determine the prevalence of "restricted diffusion" within the splenium of the corpus callosum (SOCC) on 3 Tesla (T) and 1.5T imaging systems and to establish the contribution of myelin maturation to the presence of "restricted diffusion" within the SOCC.

MATERIALS AND METHODS

The imaging database at our hospital was queried to build three cohorts of patients: (1) age < 4 months, with magnetic resonance imaging (MRI) scans done on a 3T system; (2) age < 4 months, with MRI scans done on a 1.5T system; and (3) age ≥ 4 months, with MRI scans done on a 3T system, for retrospective analysis. A total of 101 MRI scans were reviewed.

RESULTS

"Restricted diffusion" within the SOCC was present in 26 of 29 (90%) patients from cohort 1, in 1 of 37 (3%) patients from cohort 2, and in 1 of 35 (3%) patients from cohort 3. There is a significant difference in the prevalence of "restricted diffusion" in the SOCC between the three cohorts of patients.

CONCLUSIONS

"Restricted diffusion" within the SOCC may be a normal finding in infants less than 4 months of age, imaged on a 3T system. The presence of "restricted diffusion" within the splenium may serve as a potential marker of normal brain maturation.

Thanatophoric dysplasia type 1 with tectal plate dysplasia and aqueductal stenosis

INTRODUCTION

Skeletal dysplasias are a heterogeneous group of disorders comprising of more than 300 entities, many of which manifest in the prenatal period, emphasizing the importance of accurate prenatal diagnosis. Detection of a lethal skeletal dysplasia via prenatal ultrasound is often straightforward. However, establishing the specific diagnosis and detailed evaluation of intracranial anomalies are often challenging. Fetal magnetic resonance imaging (MRI) is superior to ultrasound in the detection of abnormal sulcation pattern, corpus callosal agenesis, and posterior fossa anomalies. Hence, it has the potential of delineating neuroimaging features that may not be fully elucidated by ultrasound. The objective of this article is to describe an unusual case of thanatophoric dysplasia (TD) with dysplastic tectal plate and resultant aqueductal stenosis diagnosed on fetal MRI. To the best of our knowledge, this has never been reported before in the literature. A comprehensive review of literature pertaining to TD-associated CNS abnormalities will also be included.

CONCLUSIONS

Our reported case adds to the current limited knowledge of this rare entity and emphasizes the crucial role of fetal MRI in expanding the neuroimaging phenotypes of TD.

Correction to: Congenital pial AVF along the falx cerebri with complete agenesis of the corpus callosum and bilateral parasagittal pachygyria-polymicrogyria secondary to chronic ischemia

The article which was recently published contained error. Fig. 1 was incorrectly processed as Fig. 2, resulting to identical figures during the publication the paper. Given in this article are the correct figures.

A rare case of paediatric meningioma masquerading as intra-axial lesion

Meningiomas are neoplasm arising from meningoepithelial cells, most commonly in the fifth to sixth decade of life. Meningiomas are rare in paediatric population, accounting for 0.4-4.1% of all paediatric tumours and less than 3% of paediatric brain tumours. However, meningiomas represent the most common dural based tumours in children. We describe a rare case of paediatric fibroblastic meningioma within the left middle cranial fossa masquerading as an intra-axial mass lesion. Our discussion will be centred on atypical features of paediatric meningiomas and differential diagnosis of extra-axial mass lesion in the paediatric population.

Febrile Infection-Related Epilepsy Syndrome (FIRES) with Multifocal Subcortical Infarcts, A New Imaging Phenotype

Febrile infection-related epilepsy syndrome (FIRES) is a catastrophic epileptic encephalopathy of unknown etiology which occurs predominantly in school-aged children, following a febrile illness. The term FIRES was first proposed in 2010 by van Baalen et al. The etiology of FIRES remains elusive, although most believed that it is likely related to inappropriate activation of the innate immune system. It is often a diagnosis of exclusion as it lacks specific clinical criteria and/or confirmatory tests. Familiarity with the range of imaging phenotypes associated with FIRES is crucial as this will assist timely recognition and institution of appropriate treatment plan. With this in mind, the author would like to present a rare case of FIRES with extensive subcortical infarcts, predominantly in the temporo-occipital lobes. This has never been reported before and may represent a new imaging phenotype of FIRES. A detailed literature review, focusing on the various pattern of imaging phenotypes, in relation to patients' age and clinical outcome, will also be included.

Neurometabolic Disorders of the Newborn

There is an extensive and diverse set of medical conditions affecting the neonatal brain within the spectrum of neurometabolic disorders. As such, their clinical presentations can be rather nonspecific, and can often mimic acquired entities such as hypoxic-ischemic encephalopathy and sepsis. Similarly, the radiological findings in these entities can also be frequently nonspecific, but a more detailed analysis of imaging findings (especially magnetic resonance imaging) alongside the relevant clinical details can be a rewarding experience, thus enabling a timely and targeted diagnosis. Early diagnosis of an underlying neurometabolic disorder is vital, as some of these entities are potentially treatable, and laboratory and genetic testing can be precisely targeted. Further, their detection helps with counselling families for future pregnancies. We present a review of neurometabolic disorders specific to the newborns with a focus on how neuroimaging findings match their clinical presentation patterns.

Macrocephaly: Solving the Diagnostic Dilemma

Macrocephaly is a relatively common clinical condition affecting up to 5% of the pediatric population. It is defined as an abnormally large head with an occipitofrontal circumference greater than 2 standard deviations above the mean for a given age and sex. Megalencephaly refers exclusively to brain overgrowth exceeding twice the standard deviation. Macrocephaly can be isolated and benign or may be the first indication of an underlying congenital, genetic, or acquired disorder, whereas megalencephaly is more often syndromic. Megalencephaly can be divided into 2 subtypes: metabolic and developmental, caused by genetic defects in cellular metabolism and alterations in signaling pathways, respectively. Neuroimaging plays an important role in the evaluation of macrocephaly, especially in the metabolic subtype which may not be overtly apparent clinically. This article outlines the diverse etiologies of macrocephaly, delineates their clinical and radiographic features, and suggests a clinicoradiological algorithm for evaluation.

Comprehensive genotype-phenotype correlation in lissencephaly

Malformations of cortical development (MCD) are a heterogenous group of disorders with diverse genotypic and phenotypic variations. Lissencephaly is a subtype of MCD caused by defect in neuronal migration, which occurs between 12 and 24 weeks of gestation. The continuous advancement in the field of molecular genetics in the last decade has led to identification of at least 19 lissencephaly-related genes, most of which are related to microtubule structural proteins (tubulin) or microtubule-associated proteins (MAPs). The aim of this review article is to bring together current knowledge of gene mutations associated with lissencephaly and to provide a comprehensive genotype-phenotype correlation. Illustrative cases will be presented to facilitate the understanding of the described genotype-phenotype correlation.

Intracranial hemorrhage in neonates: A review of etiologies, patterns and predicted clinical outcomes

Intracranial hemorrhage (ICH) in neonates often results in devastating neurodevelopmental outcomes as the neonatal period is a critical window for brain development. The neurodevelopmental outcomes in neonates with ICH are determined by the maturity of the brain, the location and extent of the hemorrhage, the specific underlying etiology and the presence of other concomitant disorders. Neonatal ICH may result from various inherited and acquired disorders. We classify the etiologies of neonatal ICH into eight main categories: (1) Hemorrhagic stroke including large focal hematoma, (2) Prematurity-related hemorrhage, (3) Bleeding diathesis, (4) Genetic causes, (5) Infection, (6) Trauma-related hemorrhage, (7) Tumor-related hemorrhage and (8) Vascular malformations. Illustrative cases showing various imaging patterns that can be helpful to predict clinical outcomes will be highlighted. Potential mimics of ICH in the neonatal period are also reviewed.

A child with Apert syndrome and Sturge-Weber syndrome: could fibronectin or the RAS/MAPK signaling pathway be the connection?

BACKGROUND

Apert syndrome is one of the most common craniosynostosis syndrome caused by mutation in genes encoding fibroblast growth factor receptor 2 (FGFR2). Craniosynostosis, midfacial hypoplasia, and syndactyly/symphalangism are features of this syndrome. Sturge-Weber syndrome (SWS) on the other hand is a congenital neurocutaneous disorder characterized by facial port-wine stains (PWSs) and leptomeningeal vascular capillary malformations. In 2013, the causative mutation underlying SWS (p.R183Q somatic activating mutation in the guanine nucleotide-binding protein alpha-q (GNAQ) gene) was identified. This mutation increases downstream signaling along the RAS/MAPK pathway, resulting in increased cell proliferation. The interaction between FGFR and the RAS/MAPK signaling pathway was proposed in recent years. Elevated synthesis of fibronectin in the calvaria of patients with Apert syndrome and increased fibronectin gene expression in port wine-derived fibroblasts of patients with Sturge-Weber disease have also been reported.

CASE PRESENTATION

We report a unique case of Apert and Sturge-Weber syndromes occurring in the same patient. The child was noted to demonstrate features suggestive of Apert syndrome at birth, including brachycephaly, midface hypoplasia, and syndactyly. In addition, a left-sided facial port wine stain in the forehead was noted. Magnetic resonance imaging (MRI) of the brain was performed and confirmed the diagnosis of Sturge-Weber syndrome by demonstrating the presence of left sided leptomeningeal vascular capillary malformation and left-sided cerebral hemiatrophy.

CONCLUSION

To the best of our knowledge, there has been no prior described case of Apert and Sturge-Weber syndromes occurring in the same patient. This case report identifies an area of potential research on fibronectin and derangement of the RAS/MAPK signaling pathway in relation to Apert syndrome and Sturge-Weber syndrome. In view of the rare concurrence of Apert and Sturge-Weber syndromes, the underlying pathogenesis is thought to be multifactorial, one of which may be related to either increased fibronectin gene expression or derangement of the RAS/MAPK signaling pathway.

Apert syndrome: magnetic resonance imaging (MRI) of associated intracranial anomalies

INTRODUCTION

Apert syndrome is one of the most common craniosynostosis syndrome caused by mutations in genes encoding fibroblast growth factor receptor 2 (FGFR2). It is characterized by multisuture craniosynostosis, midfacial hypoplasia, abnormal skull base development and syndactyly of all extremities. Apert syndrome is associated with a wide array of central nervous system (CNS) anomalies, possibly the cause of the common occurrence of mental deficiency in patients with Apert syndrome. These CNS anomalies can be broadly classified into two groups; (1) those that are primary malformations and (2) those that occur secondary to osseous deformity/malformation.

CONCLUSION

Familiarity with CNS anomalies associated with Apert syndrome is important to both clinicians and radiologist as it impacts on management and prognostication. Cognitive development of patients has been linked to associated CNS anomalies, timing of surgery and social aspects. These associated anomalies can be broadly classified into (1) those that are primary malformations and (2) those that occur secondary to osseous deformity/malformation, as illustrated in our review paper.

Intraventricular Glioblastoma Multiforme in A Child with L2-Hydroxyglutaric Aciduria

L2-hydroxyglutaric aciduria (L2-HGA) is a rare neurometabolic disease characterized by accumulation of L2-hydroxyglutarate (L2-HG), a potential oncometabolite resulting in significant lifetime risk for cerebral tumors. Herein, we present a case of intraventricular glioblastoma multiforme (GBM) in a 16-year-old child with L2-HGA who presented with rapid functional decline and persistent vomiting. The tumor was completely resected, and the patient remained well at 2-year follow-up. Clinicians should be aware of the usual insidious nature of the disease. Rapid deterioration is unusual and should raise the suspicion of tumor development. This case also illustrates the importance of surveillance neuroimaging in patients with L2-HGA. To the best of our knowledge, only 1 case of GBM has been reported and it was sited in the temporal lobe, unlike the unusual intraventricular location in our case.