This site is targeted at medical and radiology professionals, contains user contributed content, and material that may be confusing to a lay audience. Use of this site implies acceptance of our Terms of Use.

Air trapping

Dr Yuranga Weerakkody and Dr Bruno Di Muzio et al.

Air trapping in chest imaging refers to retention of excess gas (“air”) in all or part of the lung, especially during expiration, either as a result of complete or partial airway obstruction or as a result of local abnormalities in pulmonary compliance¹.

Although not in common usage, the term “gas trapping” is more accurate.

It is a descriptor used in lung CT seem as a decreased attenuation of pulmonary parenchyma, especially manifest as less than normal increase in attenuation during expiration acquisition. Must be differentiated from the decreased attenuation of hypoperfusion secondary to locally increased pulmonary arterial resistance¹.

The presence of air trapping can arise from a number of causes but usually suggests airway disease.

Common conditions that lead to air trapping include

asthma ³
bronchiolitis obliterans³

References

This article is in need of some more references!
You can make a difference to Radiopaedia.org by adding some relevant ones.
1. Austin JH, Müller NL, Friedman PJ et-al. Glossary of terms for CT of the lungs: recommendations of the Nomenclature Committee of the Fleischner Society. Radiology. 1996;200 (2): 327-31. Radiology (citation) - Pubmed citation
2. Webb WR, Műller NL, Naidich DP. High-resolution CT of the lung. Lippincott Williams & Wilkins. (2008) ISBN:0781769094. Read it at Google Books - Find it at Amazon
3. Tanaka N, Matsumoto T, Miura G et-al. Air trapping at CT: high prevalence in asymptomatic subjects with normal pulmonary function. Radiology. 2003;227 (3): 776-85. doi:10.1148/radiol.2273020352 - Pubmed citation
4. Arakawa H, Webb WR. Air trapping on expiratory high-resolution CT scans in the absence of inspiratory scan abnormalities: correlation with pulmonary function tests and differential diagnosis. AJR Am J Roentgenol. 1998;170 (5): 1349-53. Pubmed citation