ground-glass opacification

Ground-glass opacification/opacity (GGO) is a descriptive term referring to an area of increased attenuation in the lung on computed tomography (CT) with preserved bronchial and vascular markings. It is a non-specific sign with a wide etiology including infection, chronic interstitial disease and acute alveolar disease.

Ground glass opacification is also used in chest radiography to refer to a region of hazy lung radiopacity, often fairly diffuse, in which the edges of the pulmonary vessels may be difficult to appreciate .

The use of the term ground glass derives from the industrial technique in glassmaking whereby the surface of normal glass is roughened by grinding it.

Pathology

Etiology

Ground-glass opacities have a broad etiology:

  • normal expiration
    • on expiratory acquisitions, which can be detected if the posterior membranous wall of the trachea is flattened or bowed inwards
  • partial filling of air spaces
  • partial collapse of alveoli
  • interstitial thickening
  • inflammation
  • edema
  • fibrosis
  • lepidic proliferation of neoplasm
Morphological forms

Differential diagnosis

Broadly speaking, the differential for ground-glass opacification can be split into :

  • infectious processes (opportunistic vs non-opportunistic)
  • chronic interstitial diseases
  • acute alveolar diseases
  • other causes
Infections
Opportunistic
Non-opportunistic
Chronic interstitial diseases
Acute alveolar disease
Other causes
Rare causes

See also