Computed tomography of the pulmonary parenchyma. Part 1: Distal air-space disease.

Because of greatly enhanced contrast resolution and the advantages of cross-sectional visualization of lung anatomy, computed tomography (CT) has the potential to add significantly to the conceptualization of parenchymal lung disease. Although the value of CT has been well documented in the detection and characterization of lung nodules, the role of CT has been less clearly defined for other types of lung disease. This report describes the CT appearance of distal air-space disease. As demonstrated by the use of inflated and contrast-injected lungs obtained at autopsy, air-space disease is definable by the following: poorly marginated nodules ranging up to 1 cm in size; coalescence of nodules; air-bronchograms and air-alveolograms; ground-glass opacification; and distinct zonal patterns of distribution, including central and peripheral configurations. These patterns of air-space abnormalities are further refined by review of case material, including examples of air-space disease secondary to aspiration and primary intraalveolar disease, evaluated by the authors over a five-year period.