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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…

Embryology, Anatomy, Normal Findings, and Imaging Techniques

Anatomy of the Skull The skull is divided into three portions: the neurocranium, the face, and the base. The neurocranium is composed of the membranous portions of the occipital, parietal, frontal, and temporal bones, and is bounded inferiorly by the base of the skull, which includes the sphenoid and ethmoid bones. The face is between the forehead and chin. Routine skull radiographs include the frontal projection,…

Thyroid and Parathyroid

Thyroid Gland Embryology The name “thyroid” is derived from the Greek word for shield due to the gland's shape and relationship with the laryngeal thyroid cartilage. The human thyroid gland has a dual embryonic origin. The two thyroid cell types, follicular cells (thyrocytes) and parafollicular (C-cells), are derived from all three germ cell layers. The most abundant cells, the follicular cells, arise from the thyroid anlage.…

Neoplasia

Cancer is a leading cause of death during childhood, second only to trauma in children between the ages of 5 and 14 years. Head and neck involvement can be seen in up to 12% of childhood cancers. Lymphoma (50%) and rhabdomyosarcoma (30%) account for the majority of primary malignant pediatric head and neck tumors. Other malignant head and neck tumors include thyroid carcinoma, nasopharyngeal carcinoma, other…