Revision 18 for 'Air-space opacification (summary)'

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Air-space opacification (summary)

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 equivalent to the pathological diagnosis of pulmonary consolidation.

Reference article

This is a summary article; read more in our article on air space opacification.


  • pathophysiology
    • material fills the pulmonary tree
      • fluid: pulmonary edema 
      • pus: pneumonia
      • blood: pulmonary hemorrhage
      • cells: cancer
      • protein: alveolar proteinosis (rare)
  • investigation
    • chest x-ray
      • confirmation of consolidation and additional findings
      • assessment of:
        • severity, e.g. number of lobes involved
        • accompanying pathology, e.g. effusion
        • complications, e.g. abscess formation
    • CT chest
      • air space opacification looks very similar to the chest x-ray
      • distribution can be assessed more accurately
      • assessment of associated features is more accurate

Radiographic features

Consolidated areas are radio-opaque on chest radiograph and chest CT compared to normally air-filled lung tissue. The distribution pattern of consolidation can aid in narrowing the potential differential diagnosis.

Lobar consolidation

Where increased density/opacity is seen in individual lung lobes. Sharp delineation can be seen when consolidation reaches a fissure, since it does not cross. Air bronchograms can also be seen due to bronchi becoming visible against the dense diseased tissue. Volume loss is usually not seen.

Diffuse consolidation

Most commonly due to heart failure, resulting in other signs such increased cardiac size, Kerley B-lines, redistribution on pulmonary blood flow and pleural fluid. Other findings can include multiple ill-defined opacities progressing to diffuse spread seen in bronchopenumonia and "white out" of a lung due to progressive consolidation from bronchoalveolar carcinoma.

Multi-focal consolidation

Multiple areas of opacity seen throughout the lung most often is due to bronchopneumonia, starting from bronchi and spreading outwards. Usually ill defined with peripheral distribution. Neoplasms such as a primary malignancy or metastasis can also cause this picture.

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