Abstract: Objective  Retrospective analysis was carried out on the complete imaging data of 21 cured and discharged patients diagnosed with novel coronavirus infection by nucleic acid to investigate the shortterm changes of HRCT images of novel coronavirus pneumonia (NCP). Methods  According to the time of chest CT examination and the imaging changes,  the course of disease was divided into early stage,  peak stage and transitional stage.And HRCT findings of lung lesions at different stages were observed. Results  Totally 16 patients had positive changes in chest CT, and 5 patients had no positive findings. In the early stage (16 days,  an average of 3 days),  HRCT showed 23 groundglass opacities,  12 ground glass nodules,  1 consolidation nodule with “halo sign”; In the peak stage (511 days,  an average of 8 days),  HRCT showed 9 groundglass opacities,  17 groundglass and consolidation in combination,  6 groundglass opacities with “crazy paving sign”,  7 consolidation nodule with “halo sign”,  1 case with a small amount of pleural effusion. The number and range of lesions in peak period of critical cases were higher than that in normal cases  between two groups.Conclusion  HRCT examination can help  detect the early and subclinical NCP.Most patients were diagnosed as severe/critical two weeks after the disease,  and HRCT reexamination is suggestive for critically ill patients.

Key words: COVID19, tomography, , spiral computed