The CT findings of patients with COVID-19 in early and progressive stages are listed in Table 2 and shown in Figs. 2, 3, 4, and 5. In terms of CT characteristics, the major finding was the GGO in 38 (61.3%) of the 62 patients. In addition, GGO with consolidation was observed in 22 (35.5%) patients; rounded opacities were observed in 16 (25.8%) patients; a crazy-paving pattern was observed in 16 (25.8%) patients; an air bronchogram was observed in 14 (22.6%) patients; a halo sign was observed in 7 (11.3%) patients; a subpleural curvilinear line was observed in 6 (9.7%) patients; pleural effusion was observed in 2 (3.2%) patients; and consolidation, nodules, thoracic lymphadenopathy, and pulmonary fibrosis were observed in 1 (1.6%) patient each. No patient presented cavitation, a reticular pattern, or bronchial wall thickening. Between the early-stage group and progress-stage group, there were no significant differences in the CT findings, except for the halo sign (p = 0.013). Specifically, the halo sign was found in only the early-stage group in 20.6% of the patients.
Table 2 Comparison of CT findings and scores between two groups in patients with COVID-19
Variables Early-stage group (n = 34) Progressive-stage group (n = 28) p value
CT findings
  Ground-glass opacity 22 (64.7%) 16 (57.1%) 0.543 (χ)
  Consolidation 1 (2.9%) 0 (0%) 1.000 (χ)
  Ground-glass opacity with consolidation 11 (32.4%) 11 (39.3%) 0.570 (χ)
  Reticular pattern 0 0 –
  Nodule 1 (2.9%) 0 1.000 (χ)
  Rounded opacities 10 (29.4%) 6 (21.4%) 0.475 (χ)
  Cavitation 0 0 –
  Crazy-paving pattern 8 (23.5%) 8 (28.6%) 0.652 (χ)
  Air bronchogram 8 (23.5%) 6 (21.4%) 0.844 (χ)
  Halo sign 7 (20.6%) 0 0.013 (χ)
  Bronchial wall thickening 0 0 –
  Subpleural curvilinear line 4 (11.8%) 2 (7.1%) 0.681 (χ)
  Thoracic lymphadenopathy 0 1 (3.6%) 0.452 (χ)
  Pleural effusion or thickening 1 (2.9%) 1 (3.6%) 1.000 (χ)
  Pulmonary fibrosis 0 1 (3.6%) 0.452 (χ)
  Max diameter of lesion (cm) 4.27 ± 2.66 5.83 ± 3.76 0.059
    < 1 cm 0 1 (3.6) 0.201 (χ)
    1–2.9 cm 13 (38.2%) 5 (17.9%)
    3–4.9 cm 12 (35.3%) 10 (35.7%)
    > 5 cm 9 (26.5%) 12 (42.9%)
Distribution
  Central 1 (2.9%) 1 (3.6%) 0.961 (χ)
  Peripheral 12 (35.3%) 9 (32.1%)
  Both central and peripheral 21 (61.8%) 18 (64.3%)
CT score 4.79 ± 2.76 7.79 ± 4.62 0.004
  0–5 27 (79.4%) 10 (35.7%) 0.004 (χ)
  6–10 6 (17.6%) 12 (42.9%)
  11–15 0 3 (10.7%)
  > 15 1 (2.9%) 3 (10.7%)
COVID-19, coronavirus disease 2019
Fig. 2 A 56-year-old male with coronavirus disease 2019 in the early-stage group. a Axial non-contrast CT shows ground-glass opacities in the anterior segments of bilateral upper lobes. b Ground-glass opacity is also shown in the peripheral region of the lateral basal segment of left lower lobe. CT score = 1 (right upper lobe) + 1 (left upper lobe) + 1 (left lower lobe) = 3
Fig. 3 A 34-year-old female with coronavirus disease 2019 in the early-stage group. a Axial non-contrast CT shows halo sign in the dorsal segment of left lower lobe and multiple ground-glass opacities in the right upper lobe and the dorsal segment of the right lower lobe. b Sagittal non-contrast CT demonstrates multiple ground-glass opacities with consolidations in the right lung, mainly distributed in the periphery. CT score = 2 (right upper lobe) + 2 (right lower lobe) + 1 (left lower lobe) = 5
Fig. 4 A 40-year-old female with coronavirus disease 2019 in the progressive-stage group. a Axial non-contrast CT shows crazy-paving pattern in the anterior segment and consolidation in the posterior segment of right upper lobe. b Consolidations are noted in the bilateral lower lobes mainly in the peripheral regions, accompanied with subpleural curvilinear line. CT score = 3 (right upper lobe) + 1 (right middle lobe) + 3 (right lower lobe) + 1 (left upper lobe) + 3 (left lower lobe) = 11
Fig. 5 A 60-year-old male with coronavirus disease 2019 in the progressive-stage group. a Axial non-contrast CT in pulmonary window shows diffuse ground-glass opacities with consolidations in bilateral lungs. b Axial non-contrast CT in mediastinal window shows consolidations in bilateral lungs, with bilateral pleural effusion. CT score = 5 (right upper lobe) + 4 (right middle lobe) + 4 (right lower lobe) + 3 (left upper lobe) + 2 (left lower lobe) = 18