CT appearances and short-term changes of COVID-19 in subclinical period/ 新型冠状病毒肺炎亚临床期CT影像特征及短期演变

Objective: To explore the characteristics and short-term changes of high resolution CT (HRCT) in subclinical stage of COVID-19. Methods: The HRCT images of 17 COVID-19 patients in subclinical stage were analyzed retrospectively in Union Hospital, Tongji Medical College, Huazhong University of Science and Technology and Wuhan Jinyintan Hospital from January 15 to 31, 2020. There were 4 males and 13 females, age ranged from 25.0 to 51.0 (39.8±7.5) years, who were closely contacted with other COVID-19 patients. The follow-up CT examination was performed within 3 to 6 days after the initial CT examination in all patients. Six patients were treated using anti-virus, anti-inflammation and symptomatic therapy, while the other 11 patients were untreated. The subclinical CT findings and short-term follow-up were analyzed, and the CT changes of short-term follow-up were summarized. Results: The lesions of 17 COVID-19 patients were mainly located at the lower lobes of bilateral lungs (at the left lower lobe in 9 cases and at the right lower lobe in 10 cases in the subclinical stage, at the left lower lobe in 9 cases and at the right lower lobe in 11 cases in the short-term follow-up). The number of involved lung segments increased from 46 in the subclinical stage to 90 in the short-term follow-up. In the subclinical stage, the multiple lesions were found in 13 cases, while in the short-term follow-up, the number of cases with multiple lesions decreased by 7, however the cases with focal lesions increased by 6 and diffuse lesions by 4. The lesions were mainly distributed under the pleura (13 cases) or along the bronchovascular bundle(10 cases). In the short-term follow-up, the lesion in 1 case expanded from the subpleural area to neighbouring bronchovascular bundle. There were 3 main types of the lesions, including ground glass nodule, ground glass opacity and crazy-paving pattern. In the subclinical stage and short-term follow-up, the ground glass opacities were seen in all the 17 cases. In the short-term follow-up, the number of cases with ground glass nodules decreased by 4 and crazy-paving pattern increased by 4. In 6 patients after treatment, the multiple ground glass nodules became single one in 3 cases, and in other 3 cases the multiple ground glass opacities were getting smaller. However, the scope of lesions in 11 patients without treatment enlarged. Conclusion: The HRCT features of the COVID-19 in subcilincal stage have some charicteristics, such as small ground glass nodule, ground glass opacity along the subpleural area or along the bronchovascular bundle, and the great changes can be seen in the short-term follow-up.