Table 1.

Common imaging findings based on types of onset.

Chronic to Subacute	Acute
Subacute course of disease > chronic	Acute or subacute onset, often with a rapid progressive course
Predominantly in the lower lobes of both lungs	Diffuse, or diffuse with a predominance of the lower lung zone
Peribronchovascular bundle distribution	Peribronchovascular distribution in the lower lobes, with parallel extension to the pleura
Reticular shadows and consolidation are common	GGO and consolidation
Reduced volume of the lower lobes	Basal volume loss
Traction bronchiectasis

GGO: ground-glass opacification.