Silhouette sign application
Structures with liquid density are visible when air filled lung adjacent to them is providing a contrast. You need to know which lung is outlining each of the structure. If you are able to identify the structure in lateral view, it suggests that the lung outlining it is normal (air filled).
| Right lung outlines | Superior vena cava |
| Inferior vena cava | |
| Ascending Aorta | |
| Tracheo esopgageal stripe | |
| Right intermediate bronchus | |
| Anterior heart margin (RV and Pulmonary out flow tract) | |
| Right pulmonary artery | |
| Right diaphragm | |
| Left lung outlines | Arch of Aorta |
| Descending aorta | |
| Left pulmonary artery | |
| Posterior margin of heart | |
| Left diaphragm |