Mediastinal interfaces and lines in children : radiographic-CT correlation

Various mediastinal interfaces and lines are well known in adults, but not fully understood in children. To review the mediastinal interfaces and lines on plain radiographs in the paediatric age group with CT correlation. Soft copies of 195 sets of CT examinations and concurrent chest radiographs in 180 paediatric patients (age 1 month to 15 years) were retrospectively reviewed. The frequency of visualisation and the anatomical basis of the mediastinal interfaces and lines were assessed. The evaluated mediastinal interfaces and lines were superior vena cava interface, descending aorta interface, left paraspinal interface, azygoesophageal recess interface, right paratracheal stripe, anterior junction line and posterior junction line. Chest radiographs showed the SVC interface in 161, the descending aorta interface in 155, the left paraspinal interface in 98, the azygoesophageal recess in 94, the right paratracheal stripe in 53, the anterior junction line in 15 and the posterior junction line in 10. Non-visualisation of mediastinal interfaces and lines on plain radiographs was explained by normal anatomical difference compared with the adult and underlying intrathoracic abnormalities when they were correlated with CT. The frequency of visualisation of the SVC interface, descending aortic interface, left paraspinal interface and azygoesophageal recess fluctuated with age, while the frequency of the right paratracheal stripe, anterior junction line and posterior junction line increased with age. Awareness of the frequency of visualisation and the anatomical basis of the mediastinal interfaces and lines in paediatric patients may be helpful for interpretation of chest radiographs.