Air-space opacification (summary)

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This is a basic article for medical students and other non-radiologists

Air-space opacification is a descriptive term that refers to filling of the lung parenchyma with material that attenuates x-rays more than the unaffected surrounding lung tissue. It is the radiological correlate of the pathological diagnosis of pulmonary consolidation.

Reference article

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

Summary

  • anatomy
  • pathophysiology
    • material fills the lung parenchyma
      • fluid: pulmonary edema 
      • pus: pneumonia
      • blood: pulmonary hemorrhage
      • cells: cancer
      • protein: alveolar proteinosis (rare)
    • distribution
      • patchy
        • air-space filling is incomplete and non-contiguous
        • residual gas within the alveoli
      • lobar
        • complete filling of a lobe of the lung
        • clear delineation between consolidation and adjacent gas-filled structures
          • the remainder of the lung or in bronchi traveling through the lobe
        • no margin between consolidation and other soft-tissue density structures
          • mediastinum or diaphragm
      • multifocal
        • symmetrical or asymmetrical
        • perihilar or peripheral
        • often non-specific without clinical history and examination findings
  • role of imaging
    • confirm air-space opacification and differentiate from atelectasis or pleural effusion where possible
    • help to determine the cause, e.g. other signs of heart failure
    • identify complications, e.g. abscess formation
    • demonstrate accompanying pathology, e.g. effusion or empyema
    • determine severity and extent, e.g. number of lobes involved, uni- or bilaterality
  • common pathology

Radiographic features

Chest x-ray
  • normal air-filled lung is black
  • air-space opacification is radiopaque (white)
  • aerated bronchi
CT chest
  • air-space opacification looks very similar to the chest x-ray
    • distribution can be assessed more accurately
    • assessment of complications is more accurate
Medical student radiology curriculum