Thick soft tissue may obscure underlying structures
Black within soft tissue may represent gas
On every chest X-ray check the soft tissues, especially around the neck, the thoracic wall, and the breasts.
If a patient has very thick soft tissue due to obesity, underlying structures such as the lung markings may be obscured. Large breasts may obscure the costophrenic angles giving the impression of the presence of pleural effusions.
This close-up demonstrates a normal fat plane between layers of muscle
Fat is less dense than muscle and so appears blacker
Note that the edge of fat is smooth
Irregular areas of black within the soft tissues may represent air tracking in the subcutaneous layers (surgical emphysema)
Assessing the soft tissues
The X-ray appearances of soft tissues of the chest can be misleading. As well as hiding genuine pathology, normal soft-tissues may mimic disease.
If you are in doubt, the first thing to do is to re-examine the patient. If you are still uncertain about the X-ray appearances, then discuss the image with a radiologist.
