Air-space opacification (summary)

This

Air-space opacification is a basic article for medical students and other non-radiologists

Consolidation is a radiological sign

Reference article

This is a summary article; read more in our article on a chest radiograph or chest CT. Many things can fillair space opacification.

Summary

• pathophysiology
  • material fills the alveolar spaces, including pulmonary tree
    • fluid (heart failure), pus (pneumonia), blood (pulmonary haemorrhage) and cells (lung cancer).

      Clinical features

      Presentation

      Presentation is dependent on the underlying cause. Symptoms may include shortness of breath, productive cough +/- haemoptosis, fevers/chills/rigors and weight loss, particularly in malignancy.

      Examination

      On examination, decreased chest expansion may be noted on the affected side and dullness to percussion. On auscultation, findings include bronchial breath sounds, inspiratory crackles or crepitations, increased vocal resonance and pleural rub.

      Pathology

      Pneumonia with pus filling the alveoli is the most common cause of acute consolidation. Other acute causes include blood from haemorrhage or contusions and transudative fluid from

      : pulmonary oedema seen in heart failure.

      Chronic consolidation will be likely due to a malignant process. Bronchoalveolar carcinoma, lymphoma and lung neoplasms with post-obstructive

    • pus: pneumonia result in malignant cells causing the consolidation seen on radiograph. Chronic post-infection diseases such as organising penumonia or eosinophilic pneumonia as also causes, with
    • blood: pulmonary haemorrhage
    • cells: cancer
    • protein: alveolar proteinosis a rare cause resulting in alveoli filled with protein(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-opaque on chest radiograph and chest CT compared to normally air filled-filled lung tissue. The distribution pattern of consolidation can aid in narrowing the potential differential diagnosis.

Patchy

The air-space filling is only partial and there is, therefore, residual gas within the alveoli. 

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 towhere air-filled bronchi becomingare visible against the dense diseased tissue. Volume loss is not 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 isare due to bronchopneumonia, starting from bronchi and spreading outwards. Usually ill defined-defined with peripheral distribution. Neoplasms such as a primary malignancy or metastasis can also cause this picture.