Neuroimaging Findings of Organic Acidemias and Aminoacidopathies.

Although individual cases of inherited metabolic disorders are rare, overall they account for a substantial number of disorders affecting the central nervous system. Organic acidemias and aminoacidopathies include a variety of inborn errors of metabolism that are caused by defects in the intermediary metabolic pathways of carbohydrates, amino acids, and fatty acid oxidation. These defects can lead to the abnormal accumulation of organic acids and amino acids in multiple organs, including the brain. Early diagnosis is mandatory to initiate therapy and prevent permanent long-term neurologic impairments or death. Neuroimaging findings can be nonspecific, and metabolism- and genetics-based laboratory investigations are needed to confirm the diagnosis. However, neuroimaging has a key role in guiding the diagnostic workup. The findings at conventional and advanced magnetic resonance imaging may suggest the correct diagnosis, help narrow the differential diagnosis, and consequently facilitate early initiation of targeted metabolism- and genetics-based laboratory investigations and treatment. Neuroimaging may be especially helpful for distinguishing organic acidemias and aminoacidopathies from other more common diseases with similar manifestations, such as hypoxic-ischemic injury and neonatal sepsis. Therefore, it is important that radiologists, neuroradiologists, pediatric neuroradiologists, and clinicians are familiar with the neuroimaging findings of organic acidemias and aminoacidopathies. ©RSNA, 2018.

The Child With Macrocephaly: Differential Diagnosis and Neuroimaging Findings.

OBJECTIVE: The purpose of this article is to offer a systematic approach to the imaging of children with macrocephaly and to illustrate key neuroimaging features of common and rare but important disorders. CONCLUSION: Macrocephaly is a common clinical finding in children. Increased volume of one of the intracranial compartments can enlarge the head either prenatally or postnatally while the cranial sutures are open. Imaging plays a central role in establishing a diagnosis and guiding management.

Orbital infantile hemangioma and rhabdomyosarcoma in children: differentiation using diffusion-weighted magnetic resonance imaging.

PURPOSE: To evaluate differences in magnetic resonance imaging (MRI) appearance between infantile hemangiomas and rhabdomyosarcomas of the orbit in pediatric patients using diffusion-weighted imaging. METHODS: A multicenter retrospective review of MRIs of pediatric patients with infantile hemangiomas and rhabdomyosarcomas of the orbit was performed. MRI examinations from a total of 21 patients with infantile hemangiomas and 12 patients with rhabdomyosarcomas of the orbit were independently reviewed by two subspecialty board-certified neuroradiologists masked to the diagnosis. A freehand region of interest was placed in the mass to obtain the mean apparent diffusion coefficient (ADC) value of the mass as well as within the medulla to obtain a ratio of the ADC mass to the medulla. A t test was used to compare mean ADC and ADC ratios between the two groups. Receiver operating characteristic analysis was performed to determine ADC value and ADC ratio thresholds for differentiation of infantile hemangioma and rhabdomyosarcoma. RESULTS: There was a statistically significant difference in the mean ADC value of infantile hemangiomas compared to rhabdomyosarcomas (1527 × 10-6 mm2/s vs 782 × 10-6 mm2/s; P = 0.0001) and the ADC ratio of the lesion to the medulla (1.77 vs 0.92; P = 0.0001). An ADC threshold of <1159 × 10-6 mm2/sec and an ADC ratio of <1.38 differentiated rhabdomyosarcoma from infantile hemangioma (sensitivity 100% and 100%; specificity 100% and 100%) with area under the curve of 1.0 and 1.0, respectively. CONCLUSIONS: In conjunction with conventional MRI sequences, ADC values obtained from diffusion-weighted MRI are useful to differentiate orbital infantile hemangiomas from rhabdomyosarcomas in pediatric patients.

Back pain and scoliosis in children: When to image, what to consider.

Back pain and scoliosis in children most commonly present as benign and self-limited entities. However, persistent back pain and/or progressive scoliosis should always be taken seriously in children. Dedicated diagnostic work-up should exclude etiologies that may result in significant morbidity. Clinical evaluation and management require a comprehensive history and physical and neurological examination. A correct imaging approach is important to define a clear diagnosis and should be reserved for children with persistent symptoms or concerning clinical and laboratory findings. This article reviews the role of different imaging techniques in the diagnostic approach to back pain and scoliosis, and offers a comprehensive review of the main imaging findings associated with common and uncommon causes of back pain and scoliosis in the pediatric population.

Ventricular pseudodiverticula from intraparenchymal cerebrospinal fluid dissection secondary to high-grade obstructive hydrocephalus in children: magnetic resonance imaging findings.

We report on a series of three children who presented with a focal cerebrospinal fluid collection within the periventricular white matter of the temporal and occipital lobes in the setting of high-grade obstructive hydrocephalus. Magnetic resonance imaging showed a focal defect within the ventricular wall associated with leakage of cerebrospinal fluid into the adjacent white matter. The white matter tracts appeared primarily displaced. This entity should be referred to as ventricular pseudodiverticulum, not lined by ependymal cells, in contrast to a true ventricular diverticulum in which the cerebrospinal fluid is contained by a focal outpouching of the intact ventricular wall lined by a dilated and prolapsed layer of ependymal cells. Correct interpretation and classification of the findings may be helpful in predicting prognosis and outcome.

Compound Heterozygous Variants in ROBO1 Cause a Neurodevelopmental Disorder With Absence of Transverse Pontine Fibers and Thinning of the Anterior Commissure and Corpus Callosum.

BACKGROUND: Axonal guidance disorders are characterized by white matter tracts with an anomalous course, failure to cross the midline, or presence of anomalous white matter tracts. Diffusion tensor imaging (DTI) is a suitable noninvasive, in vivo neuroimaging tool to study axonal guidance disorders. We describe a novel disorder in a boy with compound heterozygous variants in the ROBO1 gene. PATIENT DESCRIPTION: The child was referred at age 13 months because of developmental delay. At age nine years, he had severe intellectual disability and hyperactivity. He was nonverbal and wheelchair dependent because of spastic diplegia and ataxia. Brain magnetic resonance imaging with DTI revealed marked pontine hypoplasia, thinning of the anterior commissure and corpus callosum, and absence of the transverse pontine fibers. In addition, at the level of the pons the corticospinal tracts and medial lemnisci were not clearly separated from each other. Whole exome sequencing revealed compound heterozygous variants in the ROBO1 gene. CONCLUSION: This child's neuroimaging phenotype (absence of the transverse pontine fibers and thinning of the anterior commissure and corpus callosum as shown by DTI) is suggestive of an axonal guidance disorder and supports a pathogenic role of the compound heterozygous variants in the ROBO1 gene.