Correlation of Chest CT and RT-PCR Testing for Coronavirus Disease 2019 (COVID-19) in China: A Report of 1014 Cases

Abstract

Background Chest CT is used in the diagnosis of coronavirus disease 2019 (COVID-19) and is an important complement to reverse-transcription polymerase chain reaction (RT-PCR) tests. Purpose To investigate the diagnostic value and consistency of chest CT as compared with RT-PCR assay in COVID-19. Materials and Methods This study included 1014 patients in Wuhan, China, who underwent both chest CT and RT-PCR tests between January 6 and February 6, 2020. With use of RT-PCR as the reference standard, the performance of chest CT in the diagnosis of COVID-19 was assessed. In addition, for patients with multiple RT-PCR assays, the dynamic conversion of RT-PCR results (negative to positive, positive to negative) was analyzed as compared with serial chest CT scans for those with a time interval between RT-PCR tests of 4 days or more. Results Of the 1014 patients, 601 of 1014 (59%) had positive RT-PCR results and 888 of 1014 (88%) had positive chest CT scans. The sensitivity of chest CT in suggesting COVID-19 was 97% (95% confidence interval: 95%, 98%; 580 of 601 patients) based on positive RT-PCR results. In the 413 patients with negative RT-PCR results, 308 of 413 (75%) had positive chest CT findings. Of those 308 patients, 48% (103 of 308) were considered as highly likely cases and 33% (103 of 308) as probable cases. At analysis of serial RT-PCR assays and CT scans, the mean interval between the initial negative to positive RT-PCR results was 5.1 days ± 1.5; the mean interval between initial positive to subsequent negative RT-PCR results was 6.9 days ± 2.3. Of the 1014 patients, 60% (34 of 57) to 93% (14 of 15) had initial positive CT scans consistent with COVID-19 before (or parallel to) the initial positive RT-PCR results. Twenty-four of 57 patients (42%) showed improvement on follow-up chest CT scans before the RT-PCR results turned negative. Conclusion Chest CT has a high sensitivity for diagnosis of coronavirus disease 2019 (COVID-19). Chest CT may be considered as a primary tool for the current COVID-19 detection in epidemic areas. © RSNA, 2020 Online supplemental material is available for this article. A translation of this abstract in Farsi is available in the supplement. ترجمه چکیده این مقاله به فارسی، در ضمیمه موجود است.

Figures

Figure 1:

Flowchart of this study. RT-PCR= reverse transcription polymerase chain reaction.

Figure 2:

Chest CT images of a 29-year-old man with fever for 6 days. RT-PCR assay for the SARS-CoV-2 using a swab sample was performed on February 5, 2020, with a positive result. (A column) Normal chest CT with axial and coronal planes was obtained at the onset. (B column) Chest CT with axial and coronal planes shows minimal ground-glass opacities in the bilateral lower lung lobes (yellow arrows). (C column) Chest CT with axial and coronal planes shows increased ground-glass opacities (yellow arrowheads). (D column) Chest CT with axial and coronal planes shows the progression of pneumonia with mixed ground-glass opacities and linear opacities in the subpleural area. (E column) Chest CT with axial and coronal planes shows the absorption of both ground-glass opacities and organizing pneumonia.

Figure 3:

Chest CT images of a 34-year-old man with fever for 4 days. Positive result of RT-PCR assay for the SARS-CoV-2 using a swab sample was obtained on February 8, 2020. (row A) Chest CT with lesion-magnified coronal and sagittal planes shows a nodule with reversed halo sign in the left lower lobe (yellow box) at the early stage of the pneumonia. (row B) Chest CT with different axial planes and coronal reconstruction shows bilateral multifocal ground-glass opacities. The nodular opacity resolved.

Figure 4:

Chest CT images of a 46-year-old woman with fever for 4 days. The result of RT-PCR assay for the SARS-CoV-2 using a swab sample was positive on February 4, 2020 and was negative on February 12. Three chest CT scans obtained from January 27 (column A), February 2 (column C) and February 09, 2020 (column C) show the gradual absorption of bilateral ground-glass opacities and linear consolidation.

Figure 5:

Chest CT images of a 62-year-old man with fever for 2 weeks, and dyspnea for 1 day. Negative results of RT-PCR assay for the SARS-CoV-2 using a swab samples were obtained on February 3 and 11, 2020, respectively. (column A) Chest CT with multiple axial images shows multiple ground-glass opacities in the bilateral lungs. (column B) Chest CT with multiple axial images shows enlarged multiple ground-glass opacities. (column C) Chest CT with multiple axial images shows the progression of the disease from ground-glass opacities to multifocal organizing consolidation. (D column) chest CT with multiple axial images shows partial absorption of the organizing consolidation.

Figure 6:

Chest CT images of a 63-year-old woman with fever for 11 days. Negative results of RT-PCR assay for the SARS-CoV-2 using a swab samples were obtained on February 2 and 11, 2020, respectively. (A-C) Chest CT scans show typical mixed ground-glass opacities and multifocal consolidation shadows in bilateral lungs without evidence of resolution without resolution over 16 days.

Figure 7:

Analysis of serial RT-PCR assays in correlation with serial chest CT scans. (A) The subgroup of positive to negative RT-PCR results (n = 57). (B) The subgroup of negative to positive RT-PCR results (n = 15). The horizontal axis is the time point of initial chest CT and follow-up chest CT scans relative to the time point of the consecutive two RT-PCR tests (before positive RT-PCR, negative numbers; after RT-PCR, positive numbers).