Definition of typical CT features of COVID-19
Combined with the typical imaging diagnostic standards of COVID-19 that
were reported by domestic imaging diagnosis guidelines and some
literatures (16-18), We define the cases with the following three CT
features as typical COVID-19 cases and the others as atypical cases in
this study . These three features are as follows: Firstly, density:
Multiple GGOs(Ground glass nodules) or consolidations are present.
Secondly, size: Pulmonary lobular or fusion lobule. Thirdly,
distribution: Subpleural distribution with major axis nearly parallel to
pleura and perpendicular to the bronchovascular bundle.