Interpretation of CT signs of 2019 novel coronavirus (COVID-19) pneumonia

OBJECTIVES: To characterize and interpret the CT imaging signs of the 2019 novel coronavirus (COVID-19) pneumonia in China. MATERIALS AND METHODS: The CT images of 130 patients diagnosed as COVID-19 pneumonia from several hospitals in China were collected and their imaging features were analyzed and interpreted in detail. RESULTS: Among the 130 patients, we can see (1) distribution: 14 cases with unilateral lung disease and 116 cases with bilateral disease, the distribution was mainly lobular core (99 cases) and subpleural (102 cases); (2) number: 9 cases with single lesion, 113 cases with multiple lesions, and 8 cases with diffuse distribution; (3) density: 70 cases of pure ground glass opacity (GGO), and 60 cases of GGO with consolidation; (4) accompanying signs: vascular thickening (100 cases), “parallel pleura sign” (98 cases), “paving stone sign” (100 cases), “halo sign” (18 cases), “reversed halo sign” (6 cases), pleural effusion (2 cases), and pneumonocele (2 cases). After follow-up CT examination on 35 patients, 21 cases turned better and 14 became worse. There were signs of consolidation with marginal contraction, bronchiectasis, subpleural line, or fibrous streak. CONCLUSION: GGO and consolidation are the most common CT signs of COVID-19 pneumonia, mainly with lobular distribution and subpleural distribution. The main manifestations were tissue organization and fibrosis at late stage. The most valuable features are the parallel pleura sign and the paving stone sign. KEY POINTS: • The CT signs of the COVID-19 pneumonia are mainly distributed in the lobular core, subpleural and diffused bilaterally. • The CT signs include the “parallel pleura sign,” “paving stone sign,” “halo sign,” and “reversed halo sign.” • During the follow-up, the distribution of lobular core, the fusion of lesions, and the organization changes at late stage will appear.