Pediatric Radiology
Core concepts
Know age-specific patterns: the thymus in infants (sail sign, not a mass), physiologic bowing, and normal variants. Understand the imaging of common pediatric emergencies: intussusception (target sign, ileocolic), pyloric stenosis (thickened pyloric muscle, elongated canal), malrotation with volvulus (corkscrew sign), and necrotizing enterocolitis (pneumatosis). Master the appearances of pediatric fractures, including nonaccidental trauma (metaphyseal corner fractures, rib fractures). Recognize the signs of developmental dysplasia of the hip and the role of ultrasound. Know pediatric brain tumors (medulloblastoma, pilocytic astrocytoma) and the differences in radiation sensitivity.
Traps
Do not mistake a normal thymus for a mediastinal mass. Beware overdiagnosing pneumonia in children with viral symptoms. Recognize that young children have different fracture patterns and that some findings raise suspicion for abuse. Use ultrasound first for pyloric stenosis and intussusception when appropriate.
Rule of thumb
In a vomiting infant, an olive-shaped mass with a thickened pylorus on ultrasound suggests pyloric stenosis; a target sign suggests intussusception.
Worked example
A 6-week-old with projectile vomiting: ultrasound shows a pyloric muscle thickness >3 mm and canal length >14 mm, confirming hypertrophic pyloric stenosis.