The ring around artery sign refers to a (semi-) circular radiolucency surrounding the right pulmonary artery caused by mediastinal air in the case of pneumomediastinum 1-3.
The sign was originally described on lateral chest radiographs 1-4 but can be equally appreciated on sagittal multiplanar reconstructions on a chest CT 4.
Associated findings
Any radiolucent streaks or air bubbles around the mediastinal structures, including the following other signs 2,4:
- continuous diaphragm sign and left hemidiaphragm sign
- Naclerio's V sign
- extrapleural air sign
- spinnaker sail sign
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