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

Abstract

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.

Keywords: Coronavirus infections; Pneumonia; Tomography, x-ray computed.

Conflict of interest statement

The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article.

Figures

Fig. 1

The diagram and CT images of the NCP classified according to its imaging distribution. a Lobular distribution, (b) subpleural distribution, and (c) diffuse distribution

Fig. 2

CT signs (red arrow). a “Parallel pleura sign,” b “Paving stone sign,” c Bronchiectasis, d “Vascular sign,” e “Halo sign,” f “Reversed halo sign”

Fig. 3

One patient with positive COVID-19 nucleic acid antibody had chest CT examination for five times. a Initial CT scan (day 1) showed multiple GGOs and lobular distribution. b The lesion became enlarged and the lobular distribution was more obvious, namely the “paving stone sign” (day 3). c, d CT showed the distribution of ground glass shadow in the lobular core (day 4). e, f CT manifestations turned more severe with further expansion of the area and fusion trend. The “parallel pleura sign” can be seen (day 6). g, h After treatment, GGO absorption, consolidation, marginal contraction, and bronchiectasis can be seen, indicating the formation of organization and the improvement of lesions (day 9)

Fig. 4

Another patient with positive COVID-19 nucleic acid antibody had chest CT examination twice in the same CT section. a The initial CT scan showed the patchy ground-glass density with lobular distribution and fusion trend, namely the “parallel pleura sign” and “paving stone sign”; b 2 days later, the CT manifestations progressed into diffuse ground-glass shadow in both lungs (“white lung”)