air space opacification
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 radiological studies, it presents as increased attenuation of the lung parenchyma causing obscuration of pulmonary vessels, without significant loss of volume, in the segment(s) affected. Air bronchograms can also be found .
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 edema secondary to heart failure
- pus, e.g. bacterial pneumonia
- blood, e.g. pulmonary hemorrhage
- cells, e.g. bronchoalveolar carcinoma
- protein, e.g. alveolar proteinosis
- fat, e.g. lipoid pneumonia
- gastric contents, e.g. aspiration pneumonia
- water, e.g. drowning
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:
- acute unilateral air space opacification
- acute bilateral air space opacification
- acute airspace opacification with lymphadenopathy
- chronic unilateral airspace opacification
- chronic bilateral airspace opacification
Patterns of disease
On chest radiography a number of patterns are recognized:
- lobar consolidation
- lobar lung collapse