HRCT Feature and Evolution Rule of COVID-19/ 新型冠状病毒肺炎胸部高分辨CT表现及演变规律

Objective To investigate the High Resolution CT (HRCT) feature and evolution rule of COVID‐19 Methods Forty‐five cases of COVID‐19 confirmed by RT‐PCR (reverse‐transcriptase‐polymerase‐chain‐reaction) were enrolled in this study, including 16 males and 29 females, aged from 25-88 (47 7 ± 18 2) years All patients were performed HRCT in early phase (1-7 d after symptoms onset), advanced phase (8-14 d) and recovery Phase (15-21 d) HRCT finding has involved pulmonary lobe, lesion distribution, number, size, shape, and density in three phases were evaluated by two radiologists, and the difference was compared, then the evolution rule of COVID‐19 was analyzed CT signs of lesions and pleural changes were also recorded Results Of the 45 cases, the symptoms of the whole body (such as fever) and respiratory circulatory system were more common than others (χ2 = 96 3, P<0 05) There was no significant difference in three phases in terms of involved pulmonary lobe, lesion distribution, number, size, and density (Z = 0 583, 1 726, 0 357, 3 595, 3 505, P = 0 965, 0 422, 0 837, 0 166, 0 173 respectively) The lesions distributed predominantly in inferior lobes, peripheral and peripheral plus central zone in the same phase and either single or multifocal lesions were more common than diffuse lesions However there was significant difference of lesions' shape in three phases (Z = 12 782, P = 0 002), mainly patch shadow vs fibrotic streaks (Z = -3 067, P = 0 002), patch shadow vs mass‐like (Z = -1 280, P = 0 201)and fibrotic streaks vs mass‐like (Z = -2 595, P = 0 009), and the fibrotic streaks' rate increased gradually The rate of pleural thickening and pleural effusion had no significant difference in three phases (Z = 2 912, P = 0 088), as well as the mediastinal lymphadenopathy and pericardial effusion (Z = -1 291, P = 0 197) HRCT demonstrated air bronchogram sign (n = 18, 30, 5, 40 0%, 66 7%, 11 1%), crazy‐paving sign (n = 11, 16, 5, 24 4%, 35 6%, 11 1%), halo sign (n = 14, 17, 3, 31 1%, 37 8%, 6 7%), subpleural line(n = 4, 8, 4, 8 9%, 17 8%, 8 9%), and reticular sign(n = 3, 5, 3, 6 7%, 11 1%, 6 7%)in three phases The lesions aggravated in the following four ways: (i)enlargement of lesions (31/45, 68 9%), (ii)increased lesions' number (33/45, 72 5%), (iii)density changed (39/45, 86 7%) and (iv)partial aggravation and partial absorption coexisted (12/45, 26 7%) Conclusion HRCT feature and evolution rule of COVID ‐ 19 are diverse and comprehensive Fibrotic streaks lesions' rate increases as the course of COVID‐19 pneumonia goes on, which may be one of the characteristics of this disease