Clinical Application Potentials of Ground Glass Opacities in Different Stages of Coronavirus Disease 2019

Objective: To analyze and compare the characteristics of ground glass opacities at different stages of coronavirus disease 2019 (COVID-19) on chest computed tomography (CT) images and to discuss its contribution to staging diagnoses and disease management for patients with COVID-19. Methods: Chest CT scans of 66 indigenous and 64 imported cases were collected from patients with COVID-19 in the Inner Mongolia region. Characteristics and the companion signs of ground glass opacities in the early and recovery stages of COVID-19 were analyzed and compared. Results: Of the 66 indigenous COVID-19 cases, 77.3% (51 cases) presented ground glass opacities in the early stage of the disease, while 63.7% (42 cases) had ground glass opacities in the recovery period. Notably, significantly different characteristics and companion signs of ground glass opacities were observed between the early and recovery stages. The average CT value of early-stage ground glass opacities (−329.14±143.66) HU was significantly higher than that of ground glass opacities (−616.71±89.82) HU in the recovery period. Compared with ground glass opacities in the recovery period, most early-stage ground glass opacities displayed clear edges (43 cases, 84.31% vs. 5 cases, 11.90%) and are often accompanied by paving stone signs (32 cases, 62.75% vs. 8 cases, 19.05%); thickened blood vessels (33 cases, 64.71% vs. 4 cases, 9.52%), and bronchial inflation symptoms (19 cases, 37.25% vs. 4 cases, 9.52%). The recovery period is more accompanied by irregular linear shadow than in the early stage (35 cases, 83.33% vs. 8 cases, 15.69%). There was no significant difference in the companion signs of interlobular septal thickening between the two stages (7 cases in the early stage, 13.72% vs. 2 cases in the recovery period, 4.76%). The results of the imported type are consistent with those of the indigenous type. Compared with ground glass opacities in the recovery period, most early-stage ground glass opacities displayed clear edges, while in the recovery group, the density of ground glass opacities was lower and accompanied more by irregular linear shadow. Both local and imported cases of COVID-19 showed more inflammatory consolidation and striation in the advanced stage than in the early stage. Conclusion: Compared with the ground glass opacities in the early stage, the ground glass opacities in the recovery period presented a lower density, unclear edges, and fewer signs of paving stone sign, thickened blood vessels, and bronchial inflation signs, but were more often accompanied by irregular linear shadows which are of great clinical application value for determining the course of COVID-19 and disease management.