In the advanced stage, GGO showed a significant decrease ( p < 0.05), GGO plus reticular pattern showed a significant increase ( p < 0.05), GGO plus consolidation (30.1%) showed a decreasing trend, and pleural effusion (12.8%) significantly developed compared with the early rapid progressive stage (2.3%) ( p < 0.05).
Figure 2 displays that the 7 CT signs (GGO, GGO + consolidation, microvascular dilation, air bronchogram, subpleural transparent line, thickening of the pleura, and pleural retraction) showed a downward trend with the course of the disease, 4 CT signs (consolidation, GGO + reticular, vacuolar sign, and pleural effusion) showed a trend of first ascending then descending, and 3 CT signs (subpleural line, bronchus distortion, and fibrotic strips) showed an upward trend.