14. Ground-Glass Opacities On Chest CT

Definition

  • Presence of hazy increased opacities of the lung, with preservation of bronchial and vascular margins.
    • Focal or diffuse.
  • Non-specific finding on CT and may represent various pathology (e.g., alveolar wall inflammation/thickening, partial airspace filling, a reduction of air in the alveolar airspaces, etc.).

 Acute Etiologies

  • Low lung volumes or normal expiration.
  • Pulmonary edema.
  • Aspiration.
  • Diffuse alveolar damage (e.g., pathologic correlate of ARDS).
  • Hemorrhage.
  • Infection.
    • Opportunistic: PCP, CMV, HSV.
    • Non-opportunistic: atypical pneumonia (e.g. mycoplasma), Covid-19, MERS, SARS.
  • Early ILD: acute interstitial pneumonia, acute eosinophilic pneumonia, hypersensitivity pneumonitis.
  • Drug toxicities.

Chronic Etiologies

  • Eosinophilic pneumonia.
  • Hypersensitivity pneumonitis.
  • Interstitial lung diseases.
    • Often correlates with fibrosis with evidence of traction bronchiectasis.
  • Pulmonary alveolar proteinosis.
  • Organizing pneumonia.
  • Sarcoidosis.
  • Neoplastic processes.
    • Adenocarcinoma in situ (formerly bronchoalveolar carcinoma).

 

Collins J, Stern EJ. Ground-glass opacity at CT: the ABCs. AJR Am J Roentgenol 1997;169:355-367.

El-Sherief AH et al. Clear Vision through the Haze: A practical Approach to Ground Glass Opacity.  Current Problems in Diagnostic Radiology 2014; 43(3) 140-158.