Pediatric Radiology

·         The hypothesized pathogenesis of Swyer-James syndrome involves a viral infection that arrests growth of an affected lung through an obliterative bronchiolitis. This results in hyperlucency from air trapping and diminished arterial flow. Traditionally, this was thought to be a unilateral process, but CT examinations often demonstrate scattered areas of bilateral air trapping.

·         hereditary syndromes associated with renal cysts: Tuberous sclerosis, von Hippel-Lindau disease, Zellweger's (cerebrohepatorenal) syndrome, Jeune's syndrome (thoracic asphyxiating dystrophy), and Meckel-Gruber syndrome.

·         Uterine and ovarian volumes are larger than normal in true isosexual precocious puberty, whereas enlargement of only the ovary has been reported with pseudosexual precocity. True isosexual precocity is due to the premature activation of the hypothalamic pituitary gonadal axis, whereas pseudosexual precocity refers to pubertal changes occurring independent of these actions, as in the case of a functional ovarian cyst or tumor. Multiple, small (less than 1 cm) cysts can be seen in the ovaries of normal children, as well as in children who have precocious puberty. However, the best predictor of true precocious puberty is bilateral ovarian enlargement, but unilateral ovarian enlargement associated with larger cysts is more related to pseudosexual precocity.

·         Normal neuronal migration occurs during fetal brain development as neurons migrate from the germinal matrix to the cortex along radial glial fibers. Partial or total arrest of this process leads to a migrational anomaly. These anomalies may include subependymal heterotopias (abnormal gray matter lining the ventricles), band heterotopias (an extra band of gray matter exists partially or completely underneath a normal-appearing cortex and a strip of white matter), schizencephaly (a cleft lined by gray matter extending from the outer cortex to the ventricles), polymicrogyria (too many gyri), pachygyria (abnormally thickened gyri), or lissencephaly (complete absence of gyri). Children typically present with developmental delay or seizures.

·         GRADING OF GERMINAL MATRIX HEMORRHAGE IN NEONATES

1.       Grade I: confined to the caudothalamic groove

2.       Grade II: extension into the lateral ventricle

3.       Grade III: extension into and dilation of the lateral ventricle

4.       Grade IV: extension into the adjacent parenchyma

·         The corpus callosum develops front to back, except for the rostrum (anterior genu, body, splenium, and rostrum last). This is important because an in utero insult may result in destruction of part of the corpus callosum. If posterior portions of the corpus callosum are present and anterior portions are not, this means that they were present at one point and were destroyed. If posterior portions are absent instead, this may mean that they did not develop.

·         Holoprosencephaly may follow an atypical pattern of corpus callosum development, in which the posterior portions develop and the anterior portions do not. This is termed atypical callosal dysgenesis.

·         The pituitary stalk is considered thickened if it is greater than 2 mm at the insertion of the gland. Close interval follow-up is warranted because this thickening may be a manifestation of a germinoma or Langerhans cell histiocytosis. Alternatively, the thickening may be idiopathic.

·         Trilateral retinoblastoma involves tumor in both eyes as well as in the pineal gland. As in the retina, even a fleck of calcium in the pineal gland of a child younger than 6 years old should be considered suggestive of neoplasm.

·         Fibromatosis colli is benign focal or fusiform enlargement of the sternocleidomastoid muscle in infants that usually regresses by 6-8 months of age and is thought to be due to trauma to the sternocleidomastoid muscle or to an in utero positioning abnormality. Ultrasound of the muscle demonstrates either diffuse enlargement or a focal hyperechoic mass. If there is question about the diagnosis, MR may be of use. MR should demonstrate low signal on T2-weighted images, which represents fibrosis in the sternocleidomastoid muscle.

·         CHARACTERISTIC AGES OF PEDIATRIC HIP DISORDERS

1.       Developmental dysplasia is a disorder of infants.

2.       Legg-Calvé-Perthes disease occurs in children 3-12 years of age.

3.       Slipped capital femoral epiphysis occurs in children 10-15 years old. This disorder cannot occur once the physes have fused!

·         LESIONS THAT SHOULD PROMPT A WORK-UP FOR CHILD ABUSE

1. Metaphyseal corner fractures (highly specific and sensitive for abuse)
2. Posterior rib fractures
3. Fractures of spinous processes, scapula, or sternum or compression fractures of vertebral bodies
4. Subdural hematomas, especially midline
5. Duodenal hematoma and pancreatitis