Keywords

These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

figure a

Air trapping or gas trapping (↑) refers to retention of excess gas in the secondary lobules of the lungs on expiratory scans (less than normal increase in attenuation of pulmonary parenchyma during expiration acquisition). The presence of this sign usually suggests small airways disease (bronchiolitis obliterans, chronic obstructive lung disease). Air trapping often coexists with other patterns of bronchial and bronchiolar pathology (mosaic perfusion, tree-in-bud, tram-tracking, and signet ring signs).