What is lung nodular density and atelectasis?

Lung nodular density is a measurement that indicates whether a lung nodule is malignant, states the National Center for Biotechnology Information. Atelectasis is the partial or complete collapse of a lung or its lobe, states Mayo Clinic. It develops when tiny lung air sacs deflate, which is common after surgery.

Small tissue masses in lungs, called lung nodules, are very common and are usually noncancerous, notes Mayo Clinic. The density of a nodule is measured in Hounsfield units, or HU, notes the National Center for Biotechnology Information. Studies have shown that an increase in lung nodular density indicates malignancy. In such cases, a biopsy can confirm whether the growth is cancerous.