Table 2.

Characteristic distribution of CT abnormalities.

Characteristic	Class 1	Class 2	Class 3	Class 4	Class 5	Class 6
Simple GGO	11	6	5	0	0	0
GGO with interlobular septal thickening	6	3	8	2	2	8
GGO with consolidation	3	1	11	2	2	10
Simple consolidation	1	0	6	5	2	10

Data are expressed as numbers.

Class 1. Small lesions: subpleural and with a diameter of ≤15 mm; Class 2. Coalescing small lesions: subpleural and with a diameter or long diameter ≤25 mm; Class 3. Subpleural, patchy continuous infiltrate, including circumferential infiltrate of lung peripheries; Class 4. Continuous infiltrate extending from the peripheral to central lung field, but not more than half of the ipsilateral lung field; Class 5. Infiltrate involving one entire lobe; Class 6. Continuous infiltrate extending from the peripheral to central lung field, involving at least half of the ipsilateral lung field (continuous infiltrate involving two-thirds of both lung fields is called “white lung”).

CT: Computed tomography; GGO: Ground-glass opacity.