Imaging of supratentorial intraventricular masses in children: a pictorial review-part 2.

PURPOSE: This article is the second in a two-part series aimed at exploring the spectrum of supratentorial intraventricular masses in children. In particular, this part delves into masses originating from cells of the ventricular lining, those within the septum pellucidum, and brain parenchyma cells extending into the ventricles. The aim of this series is to offer a comprehensive understanding of these supratentorial intraventricular masses, encompassing their primary clinical findings and histological definitions. METHODS: We conducted a review and analysis of relevant epidemiological data, the current genetics/molecular classifications as per the fifth edition of the World Health Organization (WHO) Classification of Tumors of the Central Nervous System (WHO CNS5), and imaging findings. Each supratentorial intraventricular mass was individually evaluated, with a detailed discussion on its clinical and histological features. RESULTS: This article covers a range of supratentorial intraventricular masses observed in children. These include colloid cysts, subependymal giant cell astrocytomas, ependymomas, gangliogliomas, myxoid glioneuronal tumors, central neurocytomas, high-grade gliomas, pilocytic astrocytomas, cavernous malformations, and other embryonal tumors. Each mass type is characterized both clinically and histologically, offering an in-depth review of their individual imaging characteristics. CONCLUSION: The WHO CNS5 introduces notable changes, emphasizing the vital importance of molecular diagnostics in classifying pediatric central nervous system tumors. These foundational shifts have significant potential to impact management strategies and, as a result, the outcomes of intraventricular masses in children.

Imaging of supratentorial intraventricular masses in children:a pictorial review- part 1.

PURPOSE: This article is the first in a two-part series designed to provide a comprehensive overview of the range of supratentorial intraventricular masses observed in children. Our primary objective is to discuss the diverse types of intraventricular masses that originate not only from cells within the choroid plexus but also from other sources. METHODS: In this article, we review relevant epidemiological data, the current genetics/molecular classification as outlined in the fifth edition of the World Health Organization's Classification of tumours of the Central Nervous System and noteworthy imaging findings. We conduct an exhaustive analysis of primary choroid plexus tumours as well as other conditions such as choroid plexus hyperplasia, choroid plexus cyst, choroid plexus xanthogranuloma, atypical teratoid rhabdoid tumour, meningioma, arteriovenous malformation and metastasis. RESULTS: We comprehensively evaluated each supratentorial intraventricular mass, providing an in-depth analysis of their unique clinical and histological characteristics. The fifth edition of the World Health Organization Classification of Tumours of the Central Nervous System introduces major modifications. These important changes could potentially have a profound impact on the management strategies and subsequent outcomes of these tumours. CONCLUSION: Intraventricular masses in children can arise from various sources. Surgical intervention is key for certain supratentorial intraventricular masses in paediatric patients, with preoperative neuroimaging essential to decide the best treatment approach, surgical or otherwise, as some cases may not require surgery.

Brain AVM compactness score in children with hereditary hemorrhagic telangiectasia.

OBJECTIVE: The brain arteriovenous malformation (BAVM) nidus compactness score (CS), determined on angiography, predicts BAVM recurrence after surgical resection among children with sporadic BAVMs. We measured the angiographic CS for BAVMs among children with hereditary hemorrhagic telangiectasia (HHT) to determine CS characteristics in this population. METHODS: A pediatric interventional neuroradiologist reviewed angiograms to determine the CS of BAVMs in children with HHT recruited to the BVMC. CS is based on overall nidus and perinidal anomalous vessel compactness. CS categories included 1 = diffuse nidus, 2 = intermediate nidus, and 3 = compact nidus. RESULTS: Forty-eight of 78 children (61.5%) with HHT and brain vascular malformations had a conventional angiogram; 47 (97.9%) angiograms were available. Fifty-four BAVMs were identified in 40 of these 47 children (85.1%). Of 54 BAVMs in children with HHT, CS was 1 in 7 (13%), 2 in 29 (53.7%), and 3 in 18 BAVMs (33.3%) compared with CS of 1 in six (26.1%), 2 in 15 (65.2%), and 3 in 2 BAVMs (8.7%) among 23 previously reported children with sporadic BAVMs, p = 0.045 (Fisher's exact). Seven children with HHT had intracranial hemorrhage: 4 had CS = 3, 1 had CS = 2, and 2 had CS = 1. CONCLUSIONS: A range of CSs exists across HHT BAVMs, suggesting it may be an angiographic measure of interest for future studies of BAVM recurrence and hemorrhage risk. Children with HHT may have more compact niduses compared to children with sporadic BAVMs. Additional research should determine whether CS affects hemorrhage risk or post-surgical recurrence risk in HHT-associated BAVMs, which could be used to direct BAVM treatment.

Predictors of the inability to achieve full oral feeding in postoperative infants with CHD.

OBJECTIVES: Poor oral feeding is a known contributor to growth challenges in neonates with complex CHD who require early surgery. Almost 60% of these infants do not achieve full oral feeding by hospital discharge. This study's objective was to identify predictors of the inability to achieve full oral feeding by discharge in neonates with complex CHD following surgical intervention with cardiopulmonary bypass. STUDY DESIGN: A retrospective analysis of a prospective study of 192 full-term neonates with complex CHD was performed. A stepwise selection logistic regression model was developed to predict oral feeding status at hospital discharge. Univariate subgroup analysis was performed with groups determined based on a CHD classification system. RESULTS: 58% of neonates (112/192) failed to achieve full oral feeding by hospital discharge. A logistic regression model identified duration of deep hypothermic circulatory arrest and reintubation as predictors of the inability to achieve full oral feeding. Among neonates who achieved full oral feeding by discharge (42%), only 7.5% did so after postoperative day 10. Brain maturation, brain injury, and preoperative oral feeding were not predictors of full postoperative oral feeding. CONCLUSIONS: Many infants with CHD fail to achieve full oral feeding by time of hospital discharge. Longer duration of deep hypothermic circulatory arrest and increased number of intubations were predictive of poor feeding after surgery. Prolonging hospitalisation solely to achieve full oral feeding after postoperative day ten is of limited utility; earlier discharge should be promoted to avoid negative impacts on neonatal neurodevelopment as unintended consequences of lengthy hospitalisations.

Brain Growth Charts for Quantitative Analysis of Pediatric Clinical Brain MRI Scans with Limited Imaging Pathology.

Background Clinically acquired brain MRI scans represent a valuable but underused resource for investigating neurodevelopment due to their technical heterogeneity and lack of appropriate controls. These barriers have curtailed retrospective studies of clinical brain MRI scans compared with more costly prospectively acquired research-quality brain MRI scans. Purpose To provide a benchmark for neuroanatomic variability in clinically acquired brain MRI scans with limited imaging pathology (SLIPs) and to evaluate if growth charts from curated clinical MRI scans differed from research-quality MRI scans or were influenced by clinical indication for the scan. Materials and Methods In this secondary analysis of preexisting data, clinical brain MRI SLIPs from an urban pediatric health care system (individuals aged ≤22 years) were scanned across nine 3.0-T MRI scanners. The curation process included manual review of signed radiology reports and automated and manual quality review of images without gross pathology. Global and regional volumetric imaging phenotypes were measured using two image segmentation pipelines, and clinical brain growth charts were quantitatively compared with charts derived from a large set of research controls in the same age range by means of Pearson correlation and age at peak volume. Results The curated clinical data set included 532 patients (277 male; median age, 10 years [IQR, 5-14 years]; age range, 28 days after birth to 22 years) scanned between 2005 and 2020. Clinical brain growth charts were highly correlated with growth charts derived from research data sets (22 studies, 8346 individuals [4947 male]; age range, 152 days after birth to 22 years) in terms of normative developmental trajectories predicted by the models (median r = 0.979). Conclusion The clinical indication of the scans did not significantly bias the output of clinical brain charts. Brain growth charts derived from clinical controls with limited imaging pathology were highly correlated with brain charts from research controls, suggesting the potential of curated clinical MRI scans to supplement research data sets. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Ertl-Wagner and Pai in this issue.

Advanced pediatric neuroimaging.

Advanced magnetic resonance neuroimaging techniques play an important adjunct role to conventional MRI sequences for better depiction and characterization of a variety of brain disorders. In this article we briefly review the basic principles and clinical utility of a select number of these techniques, including clinical functional MRI for presurgical planning, clinical diffusion tensor imaging and related techniques, dynamic susceptibility contrast perfusion imaging using gadolinium injection, and arterial spin labeling perfusion imaging. The article focuses on general principles of clinical MRI acquisition protocols, relevant factors affecting image quality, and a general framework for obtaining images for each of these techniques. We also present relevant advances for acquiring these types of imaging sequences in a clinical setting.

Magnetic resonance imaging protocols in pediatric stroke.

Neuroimaging protocols play an important role in the timely evaluation and treatment of pediatric stroke and its mimics. MRI protocols for stroke in the pediatric population should be guided by the clinical scenario and neurologic examination, with consideration of age, suspected infarct type and underlying risk factors. Acute stroke diagnosis and causes in pediatric age groups can differ significantly from those in adult populations, and delay in stroke diagnosis among children is a common problem. An awareness of pediatric stroke presentations and risk factors among pediatric emergency physicians, neurologists, pediatricians, subspecialists and radiologists is critical to ensuring timely diagnosis. Given special considerations related to unique pediatric stroke risk factors and the need for sedation in some children, expert consensus guidelines for the imaging of suspected pediatric infarct have been proposed. In this article the authors review standard and rapid MRI protocols for the diagnosis of pediatric stroke, as well as the key differences between pediatric and adult stroke imaging.

Cerebral Blood Flow of the Neonatal Brain after Hypoxic-Ischemic Injury.

OBJECTIVE: Hypoxic-ischemic encephalopathy (HIE) in infants can have long-term adverse neurodevelopmental effects and markedly reduce quality of life. Both the initial hypoperfusion and the subsequent rapid reperfusion can cause deleterious effects in brain tissue. Cerebral blood flow (CBF) assessment in newborns with HIE can help detect abnormalities in brain perfusion to guide therapy and prognosticate patient outcomes. STUDY DESIGN: The review will provide an overview of the pathophysiological implications of CBF derangements in neonatal HIE, current and emerging techniques for CBF quantification, and the potential to utilize CBF as a physiologic target in managing neonates with acute HIE. CONCLUSION: The alterations of CBF in infants during hypoxia-ischemia have been studied by using different neuroimaging techniques, including nitrous oxide and xenon clearance, transcranial Doppler ultrasonography, contrast-enhanced ultrasound, arterial spin labeling MRI, 18F-FDG positron emission tomography, near-infrared spectroscopy (NIRS), functional NIRS, and diffuse correlation spectroscopy. Consensus is lacking regarding the clinical significance of CBF estimations detected by these different modalities. Heterogeneity in the imaging modality used, regional versus global estimations of CBF, time for the scan, and variables impacting brain perfusion and cohort clinical characteristics should be considered when translating the findings described in the literature to routine practice and implementation of therapeutic interventions. KEY POINTS: · Hypoxic-ischemic injury in infants can result in adverse long-term neurologic sequelae.. · Cerebral blood flow is a useful biomarker in neonatal hypoxic-ischemic injury.. · Imaging modality, variables affecting cerebral blood flow, and patient characteristics affect cerebral blood flow assessment..

Radiographic and histologic characterisation of white matter injury in a sheep model of CHD.

Nearly one in five children with CHD is born with white matter injury that can be recognised on postnatal MRI by the presence of T1 hyperintense lesions. This pattern of white matter injury is known to portend poor neurodevelopmental outcomes, but the exact aetiology and histologic characterisation of these lesions have never been described. A fetal sheep was cannulated at gestational age 110 days onto a pumpless extracorporeal oxygenator via the umbilical vessels and supported in a fluid environment for 14.5 days. The fetus was supported under hypoxic conditions (mean oxygen delivery 16 ml/kg/day) to simulate the in utero conditions of CHD. At necropsy, the brain was fixed, imaged with MRI, and then stained to histologically identify areas of injury. Under hypoxemic in utero conditions, the fetus developed a T1 hyperintense lesion in its right frontal lobe. Histologically, this lesion was characterised by microvascular proliferation and astrocytosis without gliosis. These findings may provide valuable insight into the aetiology of white matter injury in neonates with CHD.

A Novel Phenotype of Calvarial Thickening and Increased Rates of Premature Calvarial Suture Closure in Children With Chronic Lung Disease.

PURPOSE: The purpose of this study was to characterize a novel type of calvarial thickening and provide objective measurements of skull thickness and calvarial suture morphology in patients with bronchopulmonary dysplasia. METHODS: Infants with severe bronchopulmonary dysplasia who also had undergone computed tomography (CT) scans were identified from the neonatal chronic lung disease program database. Thickness analysis was performed using Materialise Mimics. RESULTS: The chronic lung disease team treated 319 patients during the study interval of which, 58 patients (18.2%) had head CT available. Twenty-eight (48.3%) were found to have calvarial thickening. The rate of premature suture closure in the study population was 36.2% (21 of 58 patients), with 50.0% of affected cohort having evidence of premature suture closure on the first CT scan. Multivariate logistic regression identified 2 risk factors, requiring invasive ventilation at 6 months of age and fraction of inspired oxygen requirement at 6 months of age. Increased head circumference at birth protected against the development of calvarial thickening. CONCLUSIONS: We have described a novel subset of patients with chronic lung disease of prematurity who have calvarial thickening with remarkably high rates of premature closure of cranial sutures. The exact etiology of the association is unknown. In this patient population with radiographic evidence of premature suture closure, operative decision should be made after considering unequivocal evidence of elevated intracranial pressure or dysmorphology and balanced against the risk of the procedure.

A Patch-Based Deep Learning Approach for Detecting Rib Fractures on Frontal Radiographs in Young Children.

Chest radiography is the modality of choice for the identification of rib fractures in young children and there is value for the development of computer-aided rib fracture detection in this age group. However, the automated identification of rib fractures on chest radiographs can be challenging due to the need for high spatial resolution in deep learning frameworks. A patch-based deep learning algorithm was developed to automatically detect rib fractures on frontal chest radiographs in children under 2 years old. A total of 845 chest radiographs of children 0-2 years old (median: 4 months old) were manually segmented for rib fractures by radiologists and served as the ground-truth labels. Image analysis utilized a patch-based sliding-window technique, to meet the high-resolution requirements for fracture detection. Standard transfer learning techniques used ResNet-50 and ResNet-18 architectures. Area-under-curve for precision-recall (AUC-PR) and receiver-operating-characteristic (AUC-ROC), along with patch and whole-image classification metrics, were reported. On the test patches, the ResNet-50 model showed AUC-PR and AUC-ROC of 0.25 and 0.77, respectively, and the ResNet-18 showed an AUC-PR of 0.32 and AUC-ROC of 0.76. On the whole-radiograph level, the ResNet-50 had an AUC-ROC of 0.74 with 88% sensitivity and 43% specificity in identifying rib fractures, and the ResNet-18 had an AUC-ROC of 0.75 with 75% sensitivity and 60% specificity in identifying rib fractures. This work demonstrates the utility of patch-based analysis for detection of rib fractures in children under 2 years old. Future work with large cohorts of multi-institutional data will improve the generalizability of these findings to patients with suspicion of child abuse.

Age-related topographic map of magnetic resonance diffusion metrics in neonatal brains.

Accelerated maturation of brain parenchyma close to term-equivalent age leads to rapid changes in diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) metrics of neonatal brains, which can complicate the evaluation and interpretation of these scans. In this study, we characterized the topography of age-related evolution of diffusion metrics in neonatal brains. We included 565 neonates who had MRI between 0 and 3 months of age, with no structural or signal abnormality-including 162 who had DTI scans. We analyzed the age-related changes of apparent diffusion coefficient (ADC) values throughout brain and DTI metrics (fractional anisotropy [FA] and mean diffusivity [MD]) along white matter (WM) tracts. Rate of change in ADC, FA, and MD values across 5 mm cubic voxels was calculated. There was significant reduction of ADC and MD values and increase of FA with increasing gestational age (GA) throughout neonates' brain, with the highest temporal rates in subcortical WM, corticospinal tract, cerebellar WM, and vermis. GA at birth had significant effect on ADC values in convexity cortex and corpus callosum as well as FA/MD values in corpus callosum, after correcting for GA at scan. We developed online interactive atlases depicting age-specific normative values of ADC (ages 34-46 weeks), and FA/MD (35-41 weeks). Our results show a rapid decrease in diffusivity metrics of cerebral/cerebellar WM and vermis in the first few weeks of neonatal age, likely attributable to myelination. In addition, prematurity and low GA at birth may result in lasting delay in corpus callosum myelination and cerebral cortex cellularity.

Genetic and Clinical Predictors of Ataxia in Pediatric Primary Mitochondrial Disorders.

Evaluation of ataxia in children is challenging in clinical practice. This is particularly true for highly heterogeneous conditions such as primary mitochondrial disorders (PMD). This study aims to explore cerebellar and brain abnormalities identified on MRI as potential predictors of ataxia in patients with PMD and, likewise, to determine the effect of the patient's genetic profile on these predictors as well as determination of the temporal relationship of clinical ataxia with MRI findings. We evaluated clinical, radiological, and genetic characteristics of 111 PMD patients younger than 21 years of age at The Children's Hospital of Philadelphia. Data was extracted from charts. Blinded radiological evaluations were carried out by experienced neuroradiologists. Multivariate logistic regression and generalized equation estimates were used for analysis. Ataxia was identified in 41% of patients. Cerebellar atrophy or putaminal involvement with mitochondrial DNA (mtDNA) mutations (OR 1.18, 95% CI 1.1-1.3, p < 0.001) and nuclear DNA mutation with no atrophy of the cerebellum (OR 1.14, 95% CI 1.0-1.3, p = 0.007) predicted an increased likelihood of having ataxia per year of age. Central tegmental tract predicted the presence of ataxia independent of age and pathogenic variant origin (OR 9.8, 95% CI 2-74, p = 0.009). Ataxia tended to precede the imaging finding of cerebellar atrophy. Cerebellar atrophy and putaminal involvement on MRI of pediatric-onset PMD may predict the presence of ataxia with age in patients with mtDNA mutations. This study provides predicted probabilities of having ataxia per year of age that may help in family counseling and future research of the population.

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

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

Validation of Sonographic Fronto-Occipital Ratio Based on Anatomical Landmarks Compared to MR/CT-Derived Indexes in Children with Chiari II and Ventriculomegaly.

INTRODUCTION: Ultrasound (US)-based indexes such as fronto-occipital ratio (FOR) can be used to obtain an acceptable estimation of ventricular volume. Patients with colpocephaly present a unique challenge due to the shape of their ventricles. In the present study, we aimed to evaluate the validity and reproducibility of the modified US-FOR index in children with Chiari II-related ventriculomegaly. METHODS: In this retrospective study, we evaluated Chiari II patients younger than 1 year who underwent head US and MR or CT scans for ventriculomegaly evaluation. MR/CT-based FOR was measured in the axial plane by identifying the widest diameter of frontal horns, occipital horns, and the interparietal diameter (IPD). US-based FOR (US-FOR) was measured using the largest diameter based on the following landmarks: frontal horn and IPD in the coronal plane at the level of the foramen of Monro, IPD just superior to the Sylvian fissures, and occipital horn posterior to the thalami and inferior to the superior margins of the thalami. Intraclass correlation coefficients (ICCs) were used to evaluate inter-rater reliability, and Pearson correlation coefficients and Bland-Altman plots were applied to assess agreement between US and other two modalities. RESULTS: Sixty-three paired US and MR/CT exams were assessed for agreement between US-FOR and MR/CT-FOR measurements. ICC showed an excellent inter-rater reliability for US-FOR (ICC = 0.99, p < 0.001) and MR/CT-FOR (ICC = 0.99, p < 0.001) measurements. The mean (range) values based on US-FOR showed a slight overestimation in comparison with MR/CT-FOR (0.51 [0.36-0.68] vs. 0.46 [0.34-0.64]). The Pearson correlation coefficient showed high cross-modality agreement for the FOR index (r = 0.83, p < 0.001). The Bland-Altman plot showed excellent concordance between US-FOR and MR/CT-FOR with a bias of 0.05 (95% CI: -0.03 to 0.13). CONCLUSION: US-FOR in the coronal plane is a comparable tool for evaluating ventriculomegaly in Chiari II patients when compared with MR/CT-FOR, even in the context of colpocephaly.

What is the Role of Midfacial Sutures in the Development of Maxillary Hypoplasia in Children With Cleft Palate?

ABSTRACT: Maxillary hypoplasia is common in patients with cleft lip and palate (CL/P), and its etiology is incompletely understood. The purpose of this study is to evaluate facial suture patency in patients with CL/P and maxillary hypoplasia. The authors hypothesize that patients with CL/P will demonstrate higher rates of premature midfacial suture fusion in comparison to unaffected controls. Skeletally mature patients with CL/P and midface hypoplasia were identified, along with a cohort of unaffected age- and sex-matched controls. High-resolution facial computed tomography scans were evaluated for the presence of facial suture fusion. Utilizing a previously published suture fusion grading scale, the facial sutures were classified as open, partially open, closed, or pathologically absent. Thirty-one CL/P patients with midface hypoplasia were identified, with age and sex-matched controls. The frequency of intermaxillary suture fusion did not differ between patients with CL/P and unaffected controls (P  > 0.05.) Pathologic absence of the midpalatal suture was more commonly present in patients with CL/ P and midface hypoplasia in comparison to unaffected controls (P < 0.05.) The role of midfacial sutures in the development of midfacial hypoplasia seen in CLP has not previously been studied or described. Our data show that the midpalatal suture is frequently pathologically absent in patients with CL/P and maxillary hypoplasia. The authors did not identify statistically significant differences in other midfacial sutures between patients with CL/P and controls, leading us to conclude that midfacial sutures may not play a key role in the development of midfacial hypoplasia.

Pediatric Leigh Syndrome: Neuroimaging Features and Genetic Correlations.

The neurodiagnostic criteria of Leigh syndrome have not yet been clearly redefined based on the expanding of molecular etiologies. We aimed to analyze 20 years of clinical, genetic, and magnetic resonance studies from our Leigh syndrome cohort to provide a detailed description of central nervous system lesions in Leigh syndrome and their biological evolution in view of their genetic and clinical findings. Our study adds new neurodiagnostic insights to the current knowledge of Leigh syndrome, including association with overlapping syndromes, and the correlation of pathogenic genetic variants with neuroimaging phenotypes. ANN NEUROL 2020;88:218-232.

Benign longitudinal T2-hyperintense signal in the lateral cord in infancy: a cross-sectional study of spinal cord white matter maturation on magnetic resonance imaging.

BACKGROUND: Longitudinal T2-hyperintense signal is commonly seen in the spinal cord of infants and likely reflects normal unmyelinated white matter tracts, but it can be mistaken for pathology. Autopsy studies have described incomplete myelination of spinal cord in early childhood; however, the maturation timeline of the spinal cord has not been described on imaging. OBJECTIVE: The purpose of this study was to retrospectively evaluate the maturation timeline of the spinal cord on MRI to provide a baseline for image interpretation. MATERIALS AND METHODS: We retrospectively reviewed axial T2-W images of the spinal cord acquired on 1.5-tesla (T) and 3.0-T MRI in children ages 0-2 years for presence of longitudinal T2-hyperintense signal, and we subjectively graded this signal as 0 (absent) to 3 (pronounced). Further, we reviewed a summary of medical records for confounding pathology in the brain or spine. Cord signal was interpreted as normal in the clinical report by subspecialized pediatric neuroradiologists for all included children. RESULTS: We reviewed 437 MRI exams from 409 children and included 189 studies in the analysis. Longitudinal T2-hyperintense signal in the lateral cord was seen in 95% (19/20) of subjects <1 month of age and was not seen in subjects ages 21-24 months (0/15). Grade 3 signal was seen in 22% (11/50) of infants ages 0-2 months and was not seen infants older than 5 months. CONCLUSION: Characteristic symmetrical longitudinal T2 hyperintensity in the lateral spinal cord is common in infants and should not be mistaken for pathology, and it was not seen in children older than 21 months.

Primary Mitochondrial Disorders of the Pediatric Central Nervous System: Neuroimaging Findings.

Primary mitochondrial disorders (PMDs) constitute the most common cause of inborn errors of metabolism in children, and they frequently affect the central nervous system. Neuroimaging findings of PMDs are variable, ranging from unremarkable and nonspecific to florid and highly suggestive. An overview of PMDs, including a synopsis of the basic genetic concepts, main clinical symptoms, and neuropathologic features, is presented. In addition, eight of the most common PMDs that have a characteristic imaging phenotype in children are reviewed in detail. Online supplemental material is available for this article. ©RSNA, 2020.

An Important Pediatric Stroke Mimic: Hemiplegic Migraine.

Stroke is relatively rare in children but has become increasingly recognized clinically. Hemiplegic migraine (HM) is a rare subtype of migraine, with attacks typically beginning in childhood or adolescence. Attacks are characterized by migraine headaches and motor weakness, which develop over several minutes. HM may therefore mimic acute stroke; however, symptoms last less than an hour and resolve spontaneously, often without sequela.1-4 Distinction between these entities is important due to their different urgency and management. Neuroimaging is indispensible in working up patients presenting to the Emergency Department with stroke-like symptoms and can be used to distinguish between infarction and HM.