1. Chest CT Scan Signs CHEST
Ray Animesh, MD, DNB, DM, Surabhi Vyas, MD, DNB 
CHEST 
Volume 153, Issue 6, Pages (June 2018)
DOI: /j.chest
Copyright © 2018 American College of Chest Physicians Terms and Conditions

2. Figure 1
Fallen lung sign: the collapsed lung (arrow) is seen in the dependent parts of the right hemithorax in a patient who sustained a motor vehicle accident. Note massive right pneumothorax, pneumomediastinum, and subcutaneous emphysema suggestive of airway rupture.
CHEST  , DOI: ( /j.chest )
Copyright © 2018 American College of Chest Physicians Terms and Conditions

3. Figure 2
Knuckle sign: abrupt tapering of right main pulmonary artery secondary to an embolus (arrow).
CHEST  , DOI: ( /j.chest )
Copyright © 2018 American College of Chest Physicians Terms and Conditions

4. Figure 3
Bird nest sign: contrast-enhanced CT thorax scan showing irregular, intersecting areas of stranding and irregular lines present within area of ground glass opacity.
CHEST  , DOI: ( /j.chest )
Copyright © 2018 American College of Chest Physicians Terms and Conditions