Chest computed tomography (CT) findings and semiquantitative scoring of 60 patients with coronavirus disease 2019 (COVID-19): A retrospective imaging analysis combining anatomy and pathology

Abstract

In this study, we ascertained the chest CT data of 60 patients admitted to 3 hospitals in Chongqing with confirmed COVID-19. We conducted anatomical and pathological analyses to elucidate the possible reasons for the distribution, morphology, and characteristics of COVID-19 in chest CT. We also shared a semiquantitative scoring of affected lung segments, which was recommended by our local medical association. This scoring system was applied to quantify the severity of the disease. The most frequent imaging findings of COVID-19 were subpleural ground glass opacities and consolidation; there was a significant difference in semiquantitative scores between the early, progressive, and severe stages of the disease. We conclude that the chest CT findings of COVID-19 showed certain characteristics because of the anatomical features of the human body and pathological changes caused by the virus. Therefore, chest CT is a valuable tool for facilitating the diagnosis of COVID-19 and semiquantitative scoring of affected lung segments may further elucidate diagnosis and assessment of disease severity. This will assist healthcare workers in diagnosing COVID-19 and assessing disease severity, facilitate the selection of appropriate treatment options, which is important for reducing the spread of the virus, saving lives, and controlling the pandemic.

Fig 1. COVID-19 trend chart in three counties.

The population of the three counties is similar; each has a total population of between 500 000 and 600 000 and an urban population of approximately 100 000. Between February 16th and May 16th, there were no new COVID-19 patients in Dianjiang, and only 1 and 2 new cases in Zhongxian and Changshou, respectively.

Fig 2. Demographic, epidemiological, and clinical characteristics of the 60 patients with COVID-19.

A. There was no significant difference in the mean age between males (43.4, SD 13.5; range 12–69) and females (52, SD 12.6; range 29–78; P = .759). B. The numbers of patients with recent travel to Wuhan, exposure history, and unknown exposure history, were 27, 27, and 6, respectively. C. The most common clinical features were cough (33/60) and fever (31/60), and some patients developed gastrointestinal symptoms (9/60).

Fig 3. Chest CT findings of the 60 patients with COVID-19.

A. There were a significantly greater number of lesions distributed in the peripheral zone compared to the middle zone and the central zone (both P < .001). B. The lesions’ morphology was mostly conical or fan (36/48). C. GGO was the most frequent manifestation in the early stages of disease and the most frequent manifestation regardless of disease stage. However, these signs were often coexisted in chest CT.

Fig 4. Semiquantitative scores by distribution and imaging stage.

A. Lesions were mainly distributed in posterior or near posterior lung segments S¹, S², S^9, and S¹⁰; semiquantitative scores were highest in S¹⁰ (posterior basal), especially in the right lower lobe. B. The mean semiquantitative scores were significantly different between the three disease stages; early stage 3.5 (SD 2.5; (1–9), progressive stage 11 (SD 6.2 (3–23), and severe stage 26.2 (SD 3.6 (21–31), P < .001. C. There was a significant positive correlation between imaging stage and semiquantitative scores; r (correlation coefficient) = 0.841(P < .001), R² (goodness of fit) = 0.708.

Fig 5. Typical CT manifestations 1.

Chest CT images of a 68-year-old male who presented with cough and fever for 2 days. A and B. Axial CT scan (A) and sagittal reconstruction (B) shows a small area of approximately fan-shaped and subpleural GGO in the apical segment of the right upper lobe, with multiple small vascular enlargements (white arrows); the semiquantitative score = 2. C and D. Three days later, the lesion had progressed rapidly, and is displayed as a large area of fan-shaped/conical and subpleural crazy paving pattern with air bronchogram (white arrow); the semiquantitative score = 7.

Fig 6. Typical CT manifestations 2.

A and B. An initial CT scan (A) compared with a follow-up scan 27 hours later (B) showed that the GGO co-existed with consolidations (red frame) and progressed rapidly. The scope was significantly expanded, and consolidative lesions increased. The initial semiquantitative scores were left lung = 14, and right lung = 13, totaling 27; the follow-up semiquantitative scores were left lung = 19, and right lung = 17, totaling 36. C. The light density of GGO (red frame) with multiple air bronchogram, or more appropriately, bronchiectasis. Subpleural reticular pattern (yellow frame) in the apical segment of the right superior lobe. D. GGO (red frame) and reticular pattern (yellow frame) are located in the subpleural area of the left and right lung, respectively.

Fig 7. Relatively atypical CT manifestations.

A. Multifocal solid irregular nodules (white arrow) with well- or poorly defined edges are shown in the subpleural area of the inferior lobes. B. A reversed halo sign (red frame) was in the subpleural area of the inferior lobes. C. Subpleural curvilinear opacities with poorly defined edges paralleling the pleural surface are shown in the inferior lobes. D. A subpleural thin curvilinear opacity with well-defined edges paralleling the pleural surface in the inferior lobe.

Fig 8. A 34-year-old male who presented with fever for 6 days and cough for 2 days.

A. January 21, 2020. The patient’s initial CT scan showed multifocal subpleural conical GGO, locally with consolidation. The patient was diagnosed as severe by chest CT with the semiquantitative score of 25. B. January 26, 2020. The range of lesions (red frame) was enlarged but the density decreased, with a subpleural thin curvilinear lucency (yellow arrow) paralleling the pleural surface, indicating that the lesion is beginning to be absorbed. C. February 26, 2020. The patient’s post-discharge CT review confirmed the initial observation was correct; the lesions were markedly reduced, and the subpleural thin curvilinear lucency (yellow arrow) is still visible. D. March 12, 2020. On reexamination, the lesions had reduced further. However, pulmonary hypoventilation caused by lung tissue damage was also seen, shown as an uneven increase in lung tissue density due to increased X-ray attenuation.