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Air space opacification

Dr Bruno Di Muzio and Dr Frank Gaillard et al.

Air space opacification is a descriptive term that refers to filling of the pulmonary tree with material that attenuates x-rays more than the surrounding lung parenchyma. It is one of the many patterns of lung opacification and is equivalent to the pathological diagnosis of pulmonary consolidation.

In radiology studies it presents as increased attenuation of the lung parenchyma causing deletion of pulmonary vessels, without significant loss of volume on segment affected. Air bronchograms can be found ^1;2.

Pathology

Causes

The opacification is caused by fluid or solid material within the airways that causes a difference in the relative attenuation of the lung:

transudate, e.g. pulmonary oedema secondary to heart failure
pus, e.g. bacterial pneumonia
blood, e.g. pulmonary haemorrhage
cells, e.g. bronchoalveolar carcinoma
protein, e.g. alveolar proteinosis
fat, e.g. lipoid pneumonia
gastric contents due aspiration pneumonia

When considering the likely causes of airspace opacification, it is useful to determine chronicity (by reviewing previous radiographs) and considering laterality. Additionally, the presence of mediastinal or hilar lymphadenopathy further refines the massive list of differentials:

Patterns of disease

On chest radiography a number of patterns are recognised:

References

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1- Kuhlman JE, Scatarige JC, Fishman EK et-al. CT demonstration of high attenuation pleural-parenchymal lesions due to amiodarone therapy. J Comput Assist Tomogr. 1987;11 (1): 160-2. Pubmed citation
2- Silva CI, Marchiori E, Souza JúNior AS et-al. Illustrated Brazilian consensus of terms and fundamental patterns in chest CT scans. J Bras Pneumol.;36 (1): 99-123. J Bras Pneumol (full text) - doi:10.1590/S1806-37132010000100016 - Pubmed citation