CT imaging and clinical course of asymptomatic cases with COVID-19 pneumonia at admission in Wuhan, China

Abstract

Purpose: Aimed to characterize the CT imaging and clinical course of asymptomatic cases with COVID-19 pneumonia.

Methods: Asymptomatic cases with COVID-19 pneumonia confirmed by SARS-COV-2 nucleic acid testing in Renmin Hospital of Wuhan University were retrospectively enrolled. The characteristics of CT imaging and clinical feature were collected and analyzed.

Results: 58 asymptomatic cases with COVID-19 pneumonia admitted to our hospital between Jan 1, 2020 and Feb 23, 2020 were enrolled. All patients had history of exposure to SARS-CoV-2. On admission, patients had no symptoms and laboratory findings were normal. The predominant feature of CT findings in this cohort was ground glass opacity (GGO) (55, 94.8%) with peripheral (44, 75.9%) distribution, unilateral location (34, 58.6%) and mostly involving one or two lobes (38, 65.5%), often accompanied by characteristic signs. After short-term follow-up, 16 patients (27.6%) presented symptoms with lower lymphocyte count and higher CRP, mainly including fever, cough and fatigue. The evolution of lesions on CT imaging were observed in 10 patients (17.2%). The average days of hospitalization was19.80±10.82 days, and was significantly longer in progression patients (28.60±7.55 day).

Conclusion: CT imaging of asymptomatic cases with COVID-19 pneumonia has definite characteristics. Since asymptomatic infections as "covert transmitter", and some patients can progress rapidly in the short term. It is essential to pay attention to the surveillance of asymptomatic patients with COVID-19. CT scan has great value in screening and detecting patients with COVID-19 pneumonia, especially in the highly suspicious, asymptomatic cases with negative nucleic acid testing.

Keywords: Asymptomatic; Computed Tomography; Coronavirus Disease 2019(COVID-19); Ground Glass Opacity; SARS-CoV-2.

Fig. 1

The different GGO manifestations in COVID-19 pneumonia patient. A: single, pure GGO. B: Pleural parallel sign. C: Vascular thickening sign. D: Fine reticulation. E: Halo sign. F: Air bronchogram.

Fig. 2

Comparison between recheck chest CT results and first CT results in COVID-19 pneumonia patients. Situation1:Lesion absorption A1,A2:A COVID-19 pneumonia patient, CT images on Feb 20,2020 B1,B2:A COVID-19 pneumonia patient, CT images on Feb 25,2020 These four CT images mainly shows the absorption of the lesion during the course of the disease. A1 shows the lesions parallel to the pleura under the pleura of the patient's left lung. A2 shows an ill-defined, irregularly shaped lesion. After 5 days, we recheck chest CT and find out the lesion at the original location is reduced or even disappeared. The lung tissue in the original position is gradually restored and returns to normal. Situation2:Lesion improvement A1,A2:A COVID-19 pneumonia patient, CT images on Feb 13,2020 B1,B2:A COVID-19 pneumonia patient, CT images on Feb 19,2020 These four CT images mainly shows the improvement of the lesion during the course of the disease. A1 shows a large, fused lesion in the patient's right lung, and the lesions are extensive. A2 shows a small lesion under the pleura in right lung. After 6 days, we recheck chest CT and find out the lesion at the original location is reduced. The expansion of the lesion is contained. The scope of the lesion is gradually reduced. Lung lesions are getting better after treatment. Situation3:Lesion progression A1,A2:A COVID-19 pneumonia patient, CT images on Feb 9,2020 B1,B2:A COVID-19 pneumonia patient, CT images on Feb 16,2020 These four CT images mainly shows the improvement of the lesion during the course of the disease. A1 shows a large, fused lesion in the patient's left lung. A2 shows multiple lesions in both lungs. After 7 days, we recheck chest CT and find out the lesion at the original location is expanded. The expansion of the lesion is larger than before. The scope of the lesion is out of control. Diffuse or scattered ground glass-like shadows, superimposed with thin grid-like shadows, named as paving stone sign. This patient gradually showed clinical symptoms during this period.

Fig. 2

Comparison between recheck chest CT results and first CT results in COVID-19 pneumonia patients. Situation1:Lesion absorption A1,A2:A COVID-19 pneumonia patient, CT images on Feb 20,2020 B1,B2:A COVID-19 pneumonia patient, CT images on Feb 25,2020 These four CT images mainly shows the absorption of the lesion during the course of the disease. A1 shows the lesions parallel to the pleura under the pleura of the patient's left lung. A2 shows an ill-defined, irregularly shaped lesion. After 5 days, we recheck chest CT and find out the lesion at the original location is reduced or even disappeared. The lung tissue in the original position is gradually restored and returns to normal. Situation2:Lesion improvement A1,A2:A COVID-19 pneumonia patient, CT images on Feb 13,2020 B1,B2:A COVID-19 pneumonia patient, CT images on Feb 19,2020 These four CT images mainly shows the improvement of the lesion during the course of the disease. A1 shows a large, fused lesion in the patient's right lung, and the lesions are extensive. A2 shows a small lesion under the pleura in right lung. After 6 days, we recheck chest CT and find out the lesion at the original location is reduced. The expansion of the lesion is contained. The scope of the lesion is gradually reduced. Lung lesions are getting better after treatment. Situation3:Lesion progression A1,A2:A COVID-19 pneumonia patient, CT images on Feb 9,2020 B1,B2:A COVID-19 pneumonia patient, CT images on Feb 16,2020 These four CT images mainly shows the improvement of the lesion during the course of the disease. A1 shows a large, fused lesion in the patient's left lung. A2 shows multiple lesions in both lungs. After 7 days, we recheck chest CT and find out the lesion at the original location is expanded. The expansion of the lesion is larger than before. The scope of the lesion is out of control. Diffuse or scattered ground glass-like shadows, superimposed with thin grid-like shadows, named as paving stone sign. This patient gradually showed clinical symptoms during this period.

Fig. 2

Comparison between recheck chest CT results and first CT results in COVID-19 pneumonia patients. Situation1:Lesion absorption A1,A2:A COVID-19 pneumonia patient, CT images on Feb 20,2020 B1,B2:A COVID-19 pneumonia patient, CT images on Feb 25,2020 These four CT images mainly shows the absorption of the lesion during the course of the disease. A1 shows the lesions parallel to the pleura under the pleura of the patient's left lung. A2 shows an ill-defined, irregularly shaped lesion. After 5 days, we recheck chest CT and find out the lesion at the original location is reduced or even disappeared. The lung tissue in the original position is gradually restored and returns to normal. Situation2:Lesion improvement A1,A2:A COVID-19 pneumonia patient, CT images on Feb 13,2020 B1,B2:A COVID-19 pneumonia patient, CT images on Feb 19,2020 These four CT images mainly shows the improvement of the lesion during the course of the disease. A1 shows a large, fused lesion in the patient's right lung, and the lesions are extensive. A2 shows a small lesion under the pleura in right lung. After 6 days, we recheck chest CT and find out the lesion at the original location is reduced. The expansion of the lesion is contained. The scope of the lesion is gradually reduced. Lung lesions are getting better after treatment. Situation3:Lesion progression A1,A2:A COVID-19 pneumonia patient, CT images on Feb 9,2020 B1,B2:A COVID-19 pneumonia patient, CT images on Feb 16,2020 These four CT images mainly shows the improvement of the lesion during the course of the disease. A1 shows a large, fused lesion in the patient's left lung. A2 shows multiple lesions in both lungs. After 7 days, we recheck chest CT and find out the lesion at the original location is expanded. The expansion of the lesion is larger than before. The scope of the lesion is out of control. Diffuse or scattered ground glass-like shadows, superimposed with thin grid-like shadows, named as paving stone sign. This patient gradually showed clinical symptoms during this period.