key: cord-0741492-0soyxeoy
authors: Hu, Qiongjie; Guan, Hanxiong; Sun, Ziyan; Huang, Lu; Chen, Chong; Ai, Tao; Pan, Yueying; Xia, Liming
title: Early CT features and temporal lung changes in COVID-19 pneumonia in Wuhan, China
date: 2020-04-19
journal: Eur J Radiol
DOI: 10.1016/j.ejrad.2020.109017
sha: 94b766fcebbb949573887fc3c8f7f87adb13fd61
doc_id: 741492
cord_uid: 0soyxeoy

Abstract Purpose To analyse the high-resolution computed tomography (HRCT) early imaging features and the changing trend of coronavirus disease 2019 (COVID-19) pneumonia. Materials and Methods Forty-six patients with COVID-19 pneumonia who had an isolated lesion on the first positive CT were enrolled in this study. The following parameters were recorded for each lesion: sites, sizes, location (peripheral or central), attenuation (ground-glass opacity or consolidation), and other abnormalities (supply pulmonary artery dilation, air bronchogram, interstitial thickening, etc.). The follow-up CT images were compared with the previous CT scans, and the development of the lesions was evaluated. Results The lesions tended to be peripheral and subpleural. All the lesions exhibited ground-glass opacity with or without consolidation. A higher proportion of supply pulmonary artery dilation (89.13% [41/46]) and air bronchogram (69.57% [32/46]) were found. Other findings included thickening of the intralobular interstitium and a halo sign of ground glass around a solid nodule. Cavitation, calcification or lymphadelopathy were not observed. The reticular patterns were noted from the 14 days after symptoms onset in 7 of 20 patients (45%). At 22-31 days, the lesions were completely absorbed only in 2 of 7 patients(28.57%). Conclusion The typical early CT features of COVID-19 pneumonia are ground-glass opacity, and located peripheral or subpleural location, and with supply pulmonary artery dilation. Reticulation was evident after the 2nd week and persisted in half of patients evaluated in 4 weeks after the onset. Long-term follow-up is required to determine whether the reticulation represents irreversible fibrosis.

Symptoms resulting from COVID-19 include fever, cough, myalgia, fatigue, diarrhoea and vomiting, which are similar to those of the regular human flu [2] [3] [4] . Anecdotal evidence suggested that some patients were asymptomatic [3, 4] .

Computed tomography (CT) of the chest is one of the major imaging modalities according to World Health Organization and CDC guidelines [5] . The typical findings from chest CT images of patients are bilateral multiple lobular and subsegmental areas of consolidation and ground-glass opacity [2, [6] [7] [8] . However, the early imaging features of COVID-19 infection are not typical. We aimed to describe the early CT characteristics of COVID-19 pneumonia based on an isolated lesion on initial CT scans. Thus far, this information has not been previously reported. In this study, we conducted a comprehensive evaluation of the isolated lesion on the first positive CT of patients with COVID-19 pneumonia. Additionally, we presented temporal lung changes in the follow-up chest CT scans.

SARS-Cov-2 is the subject of a continuing global public health outbreak investigations. Therefore, patient consent for this retrospective study was considered exempted by our institutional review board. We chose the patients who had an isolated lesion on the first positive chest CT and who underwent the follow-up chest CT from 1 January, 2020 to 28 February, 2020 in this single center study. All patients had recent travel history to or lived in Wuhan, China (the epicenter of the COVID-19 outbreak). Certain patients had contact with other patients with a diagnosis of COVID-19 pneumonia. The patients underwent CT for fever or other symptoms including cough, myalgia, fatigue, vomiting or diarrhoea. All cases were later confirmed with a positive result to real-time fluorescence polymerase chain reaction (RT-PCR) assay for SARS-CoV-2 nucleic acid, with throat or nasopharyngeal swab specimens. Forty-six patients were ultimately included in the study.

All patients underwent non-contrast CT scanning (GE Healthcare, Philips, or Toshiba Medical Systems) of the thorax in the supine position during end-inspiration (80-120 kVp, automated tube current modulation, mA ranges from 60 to 300,rotate time 0.5s, itch 0.984:1,a slice thickness of 1.25mm.(some diffences according to the machine types).

All CT images were reviewed by two radiologists. Decisions were reached by consensus. The lesions were analysed based on sites and sizes, and the lesion size was J o u r n a l P r e -p r o o f described as small (diameter, <1 cm), medium (diameter, 1 to<3 cm), or large (diameter, ≥3 cm) [9] . The CT images were also analysed for peripheral or central location, subpleural, ground-glass opacity (GGO) or consolidation, a halo sign of ground glass around a solid nodule, supply pulmonary artery dilation, air bronchogram, interstitial thickening, and other abnormalities (pleural effusion ， cavitation, lymphadenopathy, etc). The major CT terminologies were described using internationally standard defined by the Fleischner Society glossary [10] . The location of the lesion was defined as peripheral if it was located in the outer one-third of the lung, and otherwise, it was defined as central. Supply pulmonary artery of the lesion area was compared supply pulmonary artery of the lesion area with other pulmonary artery at the same or similar normal segment.

The intervals of the follow-up CT ranged from 3 days to 31 days after the onset of initial symptoms. The CT images were compared with previous CT scans and were evaluated for lesion development.

All statistical analyses were performed using SPSS 21.0. Quantitative data were presented as the mean ± standard deviation (minimum-maximum), and the counting data were presented as the percentage of the total.

The average age of the 27 male and 19 female patients was 39.17 ±10.03 years old (range, 23-60 years). The most common symptom was fever(40/46, 86.96%) ( Table 1) . Other non-specific symptoms included cough, myalgia, fatigue, myalgia, vomiting and diarrhoea. In all, 36 of 46 patients (78.26%) had assigned to common type, and 10 of 46 patients (21.74%) had progressed to severe type [10] . None of the patients had died at the time of this writing.

The first chest CT scan was performed 1-5 days Table 3 ).

In terms of location within a lung segment, the lesions tended to be peripheral observed at 9 days after onset in one patient (Fig 6 c,d) . In 7-31 days after onset, the J o u r n a l P r e -p r o o f lesions were gradually absorbed and became irregularly linear and reticular structure, and were even completely absorbed in two patients (Fig 5) . However, the absorbed lesions were accompanied by new lesions at 10-18 days. After 10 day (the 2nd week), 12 (60%) of 20 patients had irregular linear opacities with or without associated ground-glass opacity or consolidation. Mixed and predominantly reticular patterns were noted from the 14th day in 7 of 20 patients (45%). At 22-31 days after the onset of initial symptoms, the lesions were completely absorbed in only 2 of 7 patients (28.57%, Fig 7) . Of 16 in whom the isolated lesion was located the central region on the first CT, 12 cases (75%) showed involvement of the central and perihilar regions by expanding on the follow-up chest CT (Fig 3) .

Herein we reported the early CT features of patients diagnosed with COVID-19 pneumonia. We assessed the isolated lesion on the initial positive CT and had progression on the follow-up CT. We described the CT findings on the initial positive CT in details, when patients are suggested to be in an earlier stage of the disease.

Additionally, we presented the temporal lung changes on the follow-up chest CT.

Lei et al [8] . introduced the CT findings of COVID-19 pneumonia as a case report, which showed multiple ground-glass opacities in the bilateral upper lobe lungs. Our initial experience has shown that the typical findings from chest CT images of COVID-19 pneumonia were bilateral multiple lobular consolidations and J o u r n a l P r e -p r o o f ground-glass opacity, predominantly in the lower lobes, similar to previous reports [3, 7, 12] . We found that the typical early pulmonary CT images of COVID-19 pneumonia were ground-glass opacity with or without consolidation, predominantly In our cases, five lesions had sizes less than 10 mm. We advised that the small lesions, and especially new lesions, that contained an area of ground-glass opacity required follow-up to eliminate the possibility of COVID-19 pneumonia in these high-risk groups. Particularly, it should be noted that two cases in this study were negative on the first CT and positive on the follow-up CT. Therefore, CT re-examination might be recommended for the high-risk population with a history of epidemic condition exposure. We hope that our study findings can help to ensure triage and early recognition of the COVID-19 pneumonia. This study indeed has some limitations. The limitations of this study include its retrospective nature. Secondly, the full range of COVID-19 pneumonia appearance and distribution might not have been reflected. To further elucidate the early CT imaging features and changes in the images associated with COVID-19 pneumonia, a J o u r n a l P r e -p r o o f larger sample size is needed in our next study. Besides, we evaluated the reticulation in 4 weeks after the onset. Long-term follow-up is required in future to determine whether the reticulation represents irreversible fibrosis.

In summary, the typical early CT image features of COVID-19 pneumonia were ground-glass opacity, predominantly located peripheral or subpleural location and pulmonary artery dilation. Additionally, a new small lesion that contained an area of ground-glass opacity might require follow-up CT to eliminate the possibility of COVID-19 infection in high-risk groups. Reticulation is evident after the 2nd week and persists in half of patients evaluated after 4 weeks. Long-term follow-up is required to determine whether the reticulation represents irreversible fibrosis. We hope that our study findings can facilitate early identification and management of cases of suspected COVID-19 pneumonia.

All authors declare no relationships with any companies whose products or services may be related to the subject matter of the article. J o u r n a l P r e -p r o o f J o u r n a l P r e -p r o o f

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We express our gratitude to Qihang Chen(Department of Radiology, Beijing Hospital ) for consultation on CT images.