Radiodiagnosis
Paediatric Imaging
Paediatric imaging for MBBS and NEET-PG: ultrasound for infant brain, hip and abdomen, intussusception, pyloric stenosis, double-bubble sign and non-accidental injury, mapped to NMC code RD1.7.
MedNext Academy | 3 min read
Paediatric Imaging
Paediatric imaging for MBBS and NEET-PG: ultrasound for infant brain, hip and abdomen, intussusception, pyloric stenosis, double-bubble sign and non-accidental injury, mapped to NMC code RD1.7.
This chapter covers imaging of the child, where minimising radiation and using ultrasound and MRI are guiding principles. It teaches the ultrasound approach to the infant brain, hip and abdomen, the classic signs of intussusception, pyloric stenosis and duodenal atresia, and the imaging clues to non-accidental injury.
High-yield: Paediatric Imaging
- Children are more radiosensitive than adults, so imaging follows the ALARA principle and prefers ultrasound and MRI where possible.
- Ultrasound is the first-line investigation for the infant brain through the open anterior fontanelle, for hip dysplasia and for the paediatric abdomen.
- Developmental dysplasia of the hip is assessed by ultrasound in the first months of life before the femoral head ossifies, and by radiograph thereafter.
- The target or doughnut sign on ultrasound is characteristic of intussusception, most common at the ileocolic junction in infants.
- An air or contrast enema is both diagnostic and therapeutic for ileocolic intussusception in the stable child.
- Hypertrophic pyloric stenosis shows an elongated, thickened pylorus on ultrasound in a vomiting infant, the target and cervix signs.
- The double-bubble sign on an abdominal radiograph suggests duodenal atresia, associated with Down syndrome.
- A contrast enema shows the transition zone in Hirschsprung disease, with a narrow aganglionic distal segment and dilated proximal bowel.
- The steeple sign of subglottic narrowing suggests croup, while the thumb sign of a swollen epiglottis suggests epiglottitis.
- A skeletal survey and imaging that does not match the given history raise the suspicion of non-accidental injury, with metaphyseal corner and posterior rib fractures being specific.
- MRI is the modality of choice for the paediatric brain and spine, avoiding ionising radiation while giving excellent detail.
- Necrotising enterocolitis in the neonate shows pneumatosis intestinalis and, in severe cases, portal venous gas on the abdominal radiograph.
- Bone age is assessed from a radiograph of the left hand and wrist compared against a standard atlas.
- Micturating cystourethrography evaluates vesicoureteric reflux in a child with recurrent urinary tract infection.
Classic paediatric imaging signs
- **Intussusception:** Target or doughnut sign on ultrasound; air enema is diagnostic and therapeutic.
- **Pyloric stenosis:** Elongated, thickened pylorus on ultrasound in a vomiting infant.
- **Duodenal atresia:** Double-bubble sign on radiograph; linked with Down syndrome.
- **Non-accidental injury:** Metaphyseal corner and posterior rib fractures; history that does not fit.
NMC competencies in this chapter
- **RD1.7:** Radiological investigation and interpretation in common paediatric conditions
Frequently Asked Questions
Why is ultrasound favoured in children?
Children are more radiosensitive than adults, so ultrasound, which uses no ionising radiation, is preferred as the first-line test for the infant brain, hip and abdomen wherever it can answer the clinical question.
How is intussusception imaged and treated?
Ultrasound shows the target or doughnut sign, and in a stable child an air or contrast enema is both diagnostic and therapeutic by reducing the intussusception without surgery.
What imaging findings suggest non-accidental injury?
Metaphyseal corner fractures, posterior rib fractures, fractures of different ages and injuries that do not match the given history are concerning, and a skeletal survey is performed.
What is the double-bubble sign?
It is a gas-filled stomach and proximal duodenum on an abdominal radiograph, indicating duodenal obstruction such as duodenal atresia, which is associated with Down syndrome.
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