RESULTS
Of these 139 cases, 103 cases were confirmed for COVID-19 and 36cases were confirmed other diseases(including other pneumonia, pulmonary hemorrhage, pulmonary edema and traumatic wet lung). The sensitivity, specificity and accuracy of CT are 83.33%, 20.39%, 80.58%, Of the 103 COVID-19 cases, 82(79.61%) cases were typical cases and 21(20.39%)cases were atypical cases. 65(63.11% ) cases were in the early or advanced stage, 26(25.24%) cases were in the severe or recovery stage, and 12(11.65%)were in multiple stages. Two radiologists scored the imaging signs of secondary pulmonary lobular structure of COVID-19 and other diseases. By comparing the image features of typical cases and atypical cases, there was statistical difference between the size <3cm, the density of GGO and consolidation, but there was no statistical difference between the size > 3cm and the density of mixed GGO, there is significant statistical difference between typical cases and atypical cases of distribution and location. The scores of secondary pulmonary lobular structure in typical COVID-19 (3.42±1.25) were significant different compared with atypical COVID-19 (1.51±1.34, P<0.001). The inter-observer agreement for the score of secondary pulmonary lobular structure was excellent (kappa = 0.863, P<0.05). The diagnosis of typical CT features (Fig. 3) and atypical CT features (Fig. 4) in COVID-19 are shown in table 2.The evaluation results of dynamic multi-stage images (Fig. 5) and differential diagnosis with non- COVID-19(Fig. 6) based on the image signs of secondary pulmonary lobular structure are shown in and table 3.