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Neuroimaging in Pediatric Epilepsy

Overview Epilepsy is a common pediatric neurologic disorder. In North America, the overall incidence of epilepsy is approximately 50/100,000 per year, highest for children below 5 years of age and the elderly. Children are at higher risk for developing epilepsy than adults. Atypical, idiopathic, and focal epilepsy as well as epileptic syndromes require evaluation with magnetic resonance imaging (MRI). Approximately 30% of children with epilepsy become…

Pediatric Stroke

Stroke is a leading cause of disability and death in children. Three distinct time periods can be used to categorize stroke in the pediatric population: fetal (14 weeks of gestation until the onset of labor), perinatal/neonatal (between late third trimester and the first month of life), and childhood (beyond the first month of life until adulthood). The true incidence of fetal stroke is unknown, particularly because…

Cerebrovascular Disorders

Stroke is defined as a neurologic deficit persisting for more than 24 hours and may be caused by cerebral ischemia or intracranial hemorrhage. The annual incidence of stroke in children ranges from 2 to 13 cases per 100,000 patients and is among the top 10 causes of death in childhood. Among children diagnosed with stroke, more than 40% will have major neurologic sequelae and more than…

Pediatric Brain Neoplasms

Overview Brain tumors are the most common solid pediatric tumors and are the leading cause of death in children from solid tumors. The incidence rate of all childhood primary brain and central nervous system (CNS) tumors is estimated to be 5.47 cases per 100,000 person-years. An estimated 4830 new cases of childhood primary malignant and nonmalignant brain and other CNS tumors are expected to be diagnosed…

Infection and Inflammation

Brain Infections Bacterial, viral, fungal, and parasitic organisms are all causative factors in central neurologic system (CNS) infection. Brain infection manifests as encephalitis, cerebritis, and meningitis. Encephalitis refers to diffuse infection of the brain parenchyma, whereas cerebritis is due to a more focal parenchymal infection. Meningitis refers to infection of the pia, arachnoid, and dural membranes as well as the cerebrospinal fluid (CSF). Ventriculitis is often…

Inherited Metabolic and Neurodegenerative Disorders

Inherited Metabolic Brain Disorders Inherited metabolic brain disorders produce changes in brain metabolism and structure as a result of genetic mutations. Clinically, children with metabolic brain disorders often present with nonspecific symptoms, such as hypotonia, seizures, and developmental delay, which often makes diagnosis difficult. A combination of neurologic symptoms with and without visceral manifestation and age at onset of symptoms often are important factors indicating an…

Hydrocephalus

Hydrocephalus means “water in the brain.” It is the morphologic end result of many different processes related to enlarging ventricles with compression on brain parenchyma and subarachnoid spaces leading to raised intracranial pressure (ICP). The active enlargement of cerebrospinal fluid (CSF) space in the ventricles eventually leads to loss of brain tissue. By convention, ventriculomegaly associated with increased ICP is termed hydrocephalus . It is crucial…

Congenital Brain Malformations

Advances in gene sequencing and genotype-phenotype profiling have furthered understanding of many brain malformations. Some malformations previously considered disparate in terms of gestational timing and etiology are now considered phenotypic variants of common pathways while others previously considered variants of a specific malformation are now known to result from mutations affecting disparate molecular pathways (e.g., the lissencephalies). Given the large number of congenital human brain malformations,…

Neonatal Brain Injury

A significant number of deaths and permanent neurologic disabilities occur during the first month of life, the neonatal period. During the first month of life, term infants and particularly preterm neonates are vulnerable to a wide range of adverse events that may cause brain injury. Imaging is used not only to diagnose and understand neonatal brain injury but also to predict the neurodevelopmental outcome. Because of…

Prenatal Imaging

Central nervous system (CNS) anomalies occur in 1.4 to 1.6 per 1,000 live births and 3% to 6% of still births. Whereas some anomalies can be detected as early as the first trimester (such as anencephaly), others may not develop or become apparent until later in gestation. Ultrasound is the initial imaging modality used for the assessment of fetal CNS anomalies. When ultrasound is carefully performed…

Perfusion Imaging and Magnetoencephalography

Perfusion Imaging In the cerebrovascular literature, perfusion imaging refers to an all-encompassing term of various methods to measure hemodynamically derived functional parameters in the brain. In radiology, the three most common parameters that are assessed and utilized clinically are cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT). CBV refers to the amount (volume) of blood within a given mass of brain…

Functional Magnetic Resonance Imaging

Physiologic Basis of Functional Magnetic Resonance Imaging Functional magnetic resonance imaging (fMRI) is based on the blood oxygen level–dependent (BOLD) contrast effect and neuronal activity–cerebrovascular flow coupling. Oxygenated blood (oxyhemoglobin) is diamagnetic, producing little susceptibility-related dephasing on magnetic resonance (MR) signal. Deoxyhemoglobin is paramagnetic and elicits a more prominent effect on local field homogeneity and phase coherence, resulting in signal loss. Changes in the relative concentrations…

Diffusion-Weighted Magnetic Resonance Imaging: Principles and Implementation in Clinical and Research Settings

Of the advanced magnetic resonance imaging (MRI) modalities, diffusion-weighted (DW) MRI has probably garnered the most excitement in both clinical and research settings during the past decade. Standard now in nearly every neuroimaging MR protocol, DW-MRI has demonstrated substantial clinical utility in the detection of acute ischemia, the differential diagnosis of intracranial lesions, and the evaluation of white matter. Diffusion tensor imaging (DTI) and other high-angular…

Magnetic Resonance Spectroscopy and Positron Emission Tomography

Magnetic resonance spectroscopy (MRS) capability is available in most clinical magnetic resonance (MR) scanners. The additional information from MRS allows the assessment of cellular metabolism noninvasively. For the brain in particular, it has been proved that MRS of protons or hydrogen (1H MRS) provides additional clinically relevant information for several disease processes such as brain tumors, metabolic disorders, and systemic diseases, and it is the most…

Embryology and Brain Development

The human brain undergoes four phases of development: (1) dorsal induction (primary and secondary neurulation), (2) ventral induction (patterning of the forebrain), (3) neuronal proliferation and migration, and (4) myelination. During the third week of embryogenesis, initiation of the central nervous system evolves with the development of the notochordal process. This derivative of ectoderm grows rapidly in length so that by 20 days it is converted…

Traumatic Lesions of the Skull and Face

Congenital Depressions Congenital depressions of the calvaria result from mechanical factors that occur before or during birth. During labor, calvarial depressions are caused by excessive localized pressure on the head by the bony prominences in the maternal pelvis, including the sacral promontory, pubic symphysis, and sciatic spines ( e-Fig. 23.1 ). Application of forceps to the fetal head and traction with excessive force is another less…

The Mandible

Anatomy At birth, the mandible consists of two lateral halves united in the midline at the symphysis by a bar of cartilage ( Fig. 22.1 , e-Fig. 22.2 , and Fig. 22.3 ). Bony fusion of the symphysis usually occurs before the second year, but segments of the fissures may persist beyond puberty. The body of the mandible is large at birth compared with the relatively…

Neoplasms, Neoplasm-like Lesions, and Infections of the Skull

Primary Neoplasms Primary neoplasms of the skull are rare. The most common lesions in children with a solitary nontraumatic lump on the head are dermoid tumors (61%), cephalhematomas (9%), Langerhans cell histiocytosis (LCH) (7%), and occult meningoceles and encephaloceles (4%). Osteochondromas may arise from the cartilaginous bones of the skull base. Osteoblastomas have been reported in the calvaria of infants, and aneurysmal bone cysts have been…

Craniosynostosis, Selected Craniofacial Syndromes, and Other Abnormalities of the Skull

The clinical and radiologic features of craniosynostosis result from lack of sutural formation or premature fusion across membranous sutures. The premature sutural closure prevalence is displayed in e-Table 20.1 . Normal sutures permit skull growth perpendicular to their long axes. With early closure of one suture, there is compensation and excess growth in others resulting in a craniofacial deformity ( e-Table 20.2 ; e-Fig. 20.1 and…

Prenatal Imaging

The fetal abnormalities described in this chapter are those most likely to be assessed by a pediatric radiologist who primarily performs fetal magnetic resonance imaging (MRI), computed tomography (CT), radiography, and ultrasound. These additional modalities are particularly useful for acquiring further characterization of fetal abnormalities, especially when a fetal autopsy will be declined but a couple needs to be counseled regarding future pregnancies. In most of…