Author Contributions
Conceptualization, T.F., T.H., and M.T.; methodology, M.K. (Mizuki Kimura), K.K.; formal analysis, H.Y., E.Y., M.M., and J.T.; supervision, Y.K., M.K. (Mitsuhiro Kishino), U.T. All authors have read and agreed to the published version of the manuscript.
Figure 1.
Receiver operating characteristic curve of the four readers. Reader 1, Reader 2, Reader 3, and Reader 4 had an area under the ROC curve (AUC) of 0.847, 0.849, 0.859, and 0.881, respectively. Although the AUC tended to increase with years of radiology experience, there was no significant difference between the readers (p > 0.200).
Figure 1.
Receiver operating characteristic curve of the four readers. Reader 1, Reader 2, Reader 3, and Reader 4 had an area under the ROC curve (AUC) of 0.847, 0.849, 0.859, and 0.881, respectively. Although the AUC tended to increase with years of radiology experience, there was no significant difference between the readers (p > 0.200).
Figure 2.
Percentage and number of COVID19 patients per CO-RADS category. The histogram shows the proportion of COVID19 patients per CO-RADS category. The higher the CO-RADS category, the higher the proportion of COVID-19 positive patients.
Figure 2.
Percentage and number of COVID19 patients per CO-RADS category. The histogram shows the proportion of COVID19 patients per CO-RADS category. The higher the CO-RADS category, the higher the proportion of COVID-19 positive patients.
Figure 3.
Representative computed tomography (CT) images of COVID-19 pneumonia (Case 1). Fifty-two-year-old man. The CT images show multifocal bilateral, peripheral/subpleural ground-glass opacities with consolidations. RT-PCR was positive for SARS-CoV-2. All readers diagnosed it as Category 5. COVID-19, coronavirus disease 2019; CT, computed tomography; RT-PCR, reverse transcription-polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Figure 3.
Representative computed tomography (CT) images of COVID-19 pneumonia (Case 1). Fifty-two-year-old man. The CT images show multifocal bilateral, peripheral/subpleural ground-glass opacities with consolidations. RT-PCR was positive for SARS-CoV-2. All readers diagnosed it as Category 5. COVID-19, coronavirus disease 2019; CT, computed tomography; RT-PCR, reverse transcription-polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Figure 4.
Representative CT images of COVID-19 pneumonia (Case 2). Seventy-seven-year-old female. The CT images show multifocal bilateral, peripheral/subpleural ground-glass opacities with curvilinear bands, and subpleural sparing. RT-PCR was positive for SARS-CoV-2. All readers diagnosed it as Category 5. COVID-19, coronavirus disease 2019; CT, computed tomography; RT-PCR, reverse transcription-polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Figure 4.
Representative CT images of COVID-19 pneumonia (Case 2). Seventy-seven-year-old female. The CT images show multifocal bilateral, peripheral/subpleural ground-glass opacities with curvilinear bands, and subpleural sparing. RT-PCR was positive for SARS-CoV-2. All readers diagnosed it as Category 5. COVID-19, coronavirus disease 2019; CT, computed tomography; RT-PCR, reverse transcription-polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Figure 5.
Representative CT images of a COVID-19-negative patient. Thirty-four-year-old female. The CT images show segmental consolidation with mucus plug (arrow). RT-PCR was negative for SARS-CoV-2 and she was diagnosed with community-acquired pneumonia. All readers diagnosed it as Category 2. COVID-19, coronavirus disease 2019; CT, computed tomography; RT-PCR, reverse transcription-polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Figure 5.
Representative CT images of a COVID-19-negative patient. Thirty-four-year-old female. The CT images show segmental consolidation with mucus plug (arrow). RT-PCR was negative for SARS-CoV-2 and she was diagnosed with community-acquired pneumonia. All readers diagnosed it as Category 2. COVID-19, coronavirus disease 2019; CT, computed tomography; RT-PCR, reverse transcription-polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Figure 6.
Example of a false-positive case (Case 1). Seventy-four-year-old male. The CT images show bilateral ground-glass opacities distributed peripherally to centrally with a right lung predominance. RT-PCR was negative for SARS-CoV-2. She had a history of eosinophilic pneumonia and was diagnosed with relapse of eosinophilic pneumonia. Readers 1, 2, 3, and 4 diagnosed it as Categories 3, 4, 4, and 3, respectively. CT, computed tomography; RT-PCR, reverse transcription-polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Figure 6.
Example of a false-positive case (Case 1). Seventy-four-year-old male. The CT images show bilateral ground-glass opacities distributed peripherally to centrally with a right lung predominance. RT-PCR was negative for SARS-CoV-2. She had a history of eosinophilic pneumonia and was diagnosed with relapse of eosinophilic pneumonia. Readers 1, 2, 3, and 4 diagnosed it as Categories 3, 4, 4, and 3, respectively. CT, computed tomography; RT-PCR, reverse transcription-polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Figure 7.
Example of a false-positive case (Case 2). Fifty-four-year-old female. The CT images show bilateral, peripheral posterior ground-glass opacities with consolidation with a lower lobe predominance. RT-PCR was negative for SARS-CoV-2. She had a history of medication use and was diagnosed with drug-induced pneumonia. Readers 1, 2, 3, and 4 diagnosed it as Categories 5, 4, 4, and 3, respectively. CT, computed tomography; RT-PCR, reverse transcription-polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Figure 7.
Example of a false-positive case (Case 2). Fifty-four-year-old female. The CT images show bilateral, peripheral posterior ground-glass opacities with consolidation with a lower lobe predominance. RT-PCR was negative for SARS-CoV-2. She had a history of medication use and was diagnosed with drug-induced pneumonia. Readers 1, 2, 3, and 4 diagnosed it as Categories 5, 4, 4, and 3, respectively. CT, computed tomography; RT-PCR, reverse transcription-polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Figure 8.
Example of a false-negative case. Twenty-five-year-old male. Although RT-PCR was positive for SARS-CoV-2, the CT images show no abnormal findings. All readers diagnosed it as Category 1. CT, computed tomography; RT-PCR, reverse transcription-polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Figure 8.
Example of a false-negative case. Twenty-five-year-old male. Although RT-PCR was positive for SARS-CoV-2, the CT images show no abnormal findings. All readers diagnosed it as Category 1. CT, computed tomography; RT-PCR, reverse transcription-polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Table 1.
CO-RADS categories and the corresponding level of suspicion for pulmonary involvement of COVID-19.
Table 1.
CO-RADS categories and the corresponding level of suspicion for pulmonary involvement of COVID-19.
| Level of Suspicion for Pulmonary Involvement of COVID-19 | Summary |
---|
CO-RADS 0 | Not interpretable | Scan technically insufficient for assigning a score |
CO-RADS 1 | Very low | Normal or noninfectious |
CO-RADS 2 | Low | Typical for other infection but not COVID-19 |
CO-RADS 3 | Indeterminate | Features compatible with COVID-19, but also other diseases |
CO-RADS 4 | High | Suspicious for COVID-19 |
CO-RADS 5 | Very high | Typical COVID-19 |
CO-RADS 6 | Proven | RT-PCR positive for SARS-CoV-2 |
Table 2.
Characteristics of patients.
Table 2.
Characteristics of patients.
Parameter | COVID-19 Positive (76) | COVID-19 Negative (78) | All (144) | p COVID-19 Positive vs. Negative |
---|
Age (mean ± standard deviation (SD); range) | 57.1 ± 19.3 | 65.4 ± 17.5 | 61.3 ± 18.8 | 0.006 |
21–90 | 24–93 | 21–93 |
Sex (n, % men) | 54, 71.1% | 47, 60.3% | 101, 70.1% | 0.215 |
Comorbidities (n, %) | | | | |
Cancer | 9, 11.8% | 30, 38.5% | 39, 27.1% | <0.001 |
Cardiovascular disease | 28, 36.8% | 24, 30.8% | 52, 36.1% | 0.531 |
Lung disease | 12, 15.8% | 23, 29.5% | 35, 24.3% | 0.066 |
Collagen disease | 5, 6.6% | 16, 20.5% | 21, 14.6% | 0.022 |
Diabetes | 10, 13.2% | 7, 9.0% | 17, 11.8% | 0.568 |
Table 3.
List of diagnoses in COVID-19-negative patients.
Table 3.
List of diagnoses in COVID-19-negative patients.
Pneumonia Other than COVID-19 | 36 |
---|
(Community-acquired pneumonia) | (29) |
(Interstitial pneumonia) | (4) |
(Drug-induced pneumonia) | (1) |
(Eosinophilic pneumonia) | (1) |
(Lung abscess) | (1) |
Pulmonary edema | 5 |
Atelectasis | 4 |
Lung tumor | 3 |
Pleuritis | 2 |
Emphysema | 1 |
Normal | 27 |
Total | 78 |
Table 4.
Diagnostic performance and interobserver agreement of readers.
Table 4.
Diagnostic performance and interobserver agreement of readers.
| Sensitivity | Specificity | AUC [95% CI] | ICC [95% CI] |
---|
Reader 1 | 80.3% | 84.6% | 0.847 [0.784–0.910] | 0.800 [0.735–0.850] |
Reader 2 | 90.8% | 60.3% | 0.849 [0.787–0.911] | 0.874 [0.830–0.907] |
Reader 3 | 85.9% | 69.2% | 0.904 [0.800–0.919] | 0.855 [0.806–0.893] |
Reader 4 | 93.4% | 51.3% | 0.881 [0.826–0.935] | 0.829 [0.772–0.873] |
Average of readers | 87.8% | 66.4% | 0.859 | 0.840 |
Table 5.
Characteristics of false-positive cases in chest CT.
Table 5.
Characteristics of false-positive cases in chest CT.
No | Sex | Age | CO-RADS Category (Median of 4 Readers) | Diagnoses |
---|
False-positive | (Final diagnoses) |
1 | Male | 82 | 4 | Community-acquired pneumonia |
2 | Male | 59 | 4 | Community-acquired pneumonia |
3 | Male | 93 | 5 | Community-acquired pneumonia |
4 | Male | 73 | 4 | Community-acquired pneumonia |
5 | Female | 77 | 4 | Community-acquired pneumonia |
6 | Male | 77 | 4 | Interstitial pneumonia |
7 | Female | 54 | 4 | Drug-induced pneumonia |
8 | Male | 74 | 4 | Eosinophilic pneumonia |
9 | Female | 90 | 4 | Pulmonary edema |
10 | Female | 26 | 4 | Pleuritis |
Table 6.
Characteristics of false-negative cases in chest CT.
Table 6.
Characteristics of false-negative cases in chest CT.
No | Sex | Age | CO-RADS Category (Median of 4 Readers) | Onset to CT Duration (days) | Finding on Chest CT | Symptoms |
---|
| | | | Fever | Fatigue | Cough | Dyspnea |
---|
1 | Male | 25 | 2 | 9 | Atelectasis | P | P | P | P |
---|
2 | Female | 24 | 1 | 19 | Without abnormal findings | N | N | P | P |
3 | Female | 25 | 1 | 11 | Without abnormal findings | N | N | P | N |
4 | Female | 30 | 1 | 26 | Without abnormal findings | N | N | P | N |
5 | Male | 90 | 1 | 5 | Without abnormal findings | P | N | N | P |
6 | Female | 25 | 1 | 25 | Without abnormal findings | P | N | N | P |