Table 2.

Radiological Society of North America-Proposed Reporting Language (5).

CT category	Imaging findings
Typical	Peripheral, bilateral GGOa with or without consolidation or visible intralobular lines (“crazy-paving”) Multifocal GGO of rounded morphology with or without consolidation or visible intralobular lines (“crazy-paving”) Reverse halo sign or other findings of organizing pneumonia (seen later in the disease)
Indeterminate	Absence of typical features and presence of: Multifocal, diffuse, perihilar, or unilateral GGO with or without consolidation, lacking a specific distribution and being nonrounded or nonperipheral. Few, very small GGO with a nonrounded and nonperipheral distribution
Atypical	Absence of typical or indeterminate features and presence of: Isolated lobar or segmental consolidation without GGO Discrete small nodules (centrilobular; “tree in-bud”) Lung cavitation Smooth interlobular septal thickening with pleural effusion
Negative	No features to suggest pneumonia.

^aGGO = ground-glass opacity.