Pediatric Radiology
Core framework
Pediatric questions reward age-based pattern recognition and dose consciousness. Know the developmental milestones of ossification, the Salter-Harris classification, and normal variants that mimic disease (physiologic periosteal reaction, accessory ossification centers, thymus).
Body imaging
Neonatal bowel: malrotation with volvulus shows a corkscrew sign and requires emergent surgery; necrotizing enterocolitis shows pneumatosis intestinalis and portal venous gas; hypertrophic pyloric stenosis shows a thickened pyloric muscle (>3 mm) and elongated canal (>14–15 mm) in a 3–6-week-old. Intussusception in a toddler is reduced with an air or contrast enema if there is no perforation or peritonitis. Hirschsprung disease presents with a transition zone in the rectosigmoid.
Chest and CNS
Neonatal respiratory distress: RDS (preterm, low volume, reticulogranular), TTN (term, perihilar streaking, fluid in fissures), and meconium aspiration (term, hyperinflation, patchy opacities). Congenital diaphragmatic hernia presents with bowel in the chest and mediastinal shift. In the CNS, know neonatal germinal matrix hemorrhage (grade I–IV) and the posterior fossa tumors of childhood.
Child abuse
Classic metaphyseal lesions (corner fractures), posterior rib fractures, and multiple fractures of differing ages are highly specific for nonaccidental trauma. A skeletal survey is indicated in children under 2 years with suspected abuse.
Traps and rule of thumb
Traps: misinterpreting physiologic periosteal reaction as child abuse; forgetting that a normal thymus can mimic a mass (it does not compress the airway); ordering CT when ultrasound or MRI would answer the question.
Rule of thumb: in a young infant, "corner fracture plus posterior rib fracture equals nonaccidental trauma until proven otherwise."