Consolidation

The following are radiological criteria to call a shadow on CXR consolidation: 

1. Lobar or Segmental Density: The density should either correspond to the lobe or lung segment. 
2. Air Bronchogram: Presence of air bronchogram would confirm an alveolar process.
3. No Loss of Lung Volume: Lung volumes increase in early stages of consolidation. In later stages there can be some amount of loss of lung volume due to secretions obstructing airways. As a general rule, there is no significant loss of lung volume in consolidation.