COVID-19 pneumonia imaging classification according to the CT findingsa
| COVID-19 Pneumonia Imaging Classification | Rationale | CT Findings |
|---|---|---|
| Typical appearance | Commonly reported imaging features of greater specificity for COVID-19 pneumonia | Peripheral, bilateral GGOs with or without consolidation or visible intralobular lines (crazy-paving) |
| Multifocal GGOs 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 | Nonspecific imaging features of COVID-19 pneumonia | Absence of typical features AND |
| Presence of multifocal, diffuse, perihilar, or unilateral GGO with or without consolidation lacking a specific distribution; they are nonrounded or nonperipheral | ||
| Few very small GGOs with a nonrounded and nonperipheral distribution | ||
| Negative | Uncommonly or not reported features of COVID-19 pneumonia | Absence of typical or indeterminate features AND |
| Presence of isolated lobar or segmental consolidation without GGO | ||
| Discrete small nodules (centrilobular, tree-in-bud sign) | ||
| Lung cavitation | ||
| Smooth interlobular septal thickening with pleural effusion | ||
| OR no abnormal findings |
Note:—GGO indicates ground glass opacity.
↵a Adapted from the proposed Radiological Society of North America and British Society of Thoracic Imaging chest CT classification for reporting of COVID-19 pneumonia.15,16