Chest CT in the Emergency Department for Diagnosis of COVID-19 Pneumonia: Dutch Experience

BACKGROUND: Clinicians need rapid and reliable diagnosis of coronavirus disease 2019 (COVID-19) for proper risk stratification, isolation strategies, and treatment decisions. PURPOSE: To assess the real-life performance of radiologist emergency department chest CT interpretation for diagnosing COVID-19 during the acute phase of the pandemic, using the COVID-19 reporting and data system (CO-RADS). MATERIALS AND METHODS: This retrospective multicenter study included consecutive patients who presented to emergency departments in six medical centers between March and April 2020 with moderate to severe upper respiratory symptoms suspicious for COVID-19. As part of clinical practice, chest CT was obtained for primary workup and scored using the 5-point CO-RADS scheme for suspicion of COVID-19. CT was compared with SARS-CoV-2 RT-PCR, and a clinical reference standard established by a multidisciplinary group of clinicians based on RT-PCR, COVID-19 contact history, oxygen therapy, timing of RT-PCR testing and likely alternative diagnosis. Performance of CT was estimated using area under the receiver operating characteristics curve (AUC) analysis and diagnostic odds ratios (OR) against both reference standards. Subgroup analysis was performed based on symptom duration grouped presentations of < 48 hours, 48 hours through 7 days, and > 7 days. RESULTS: A total of 1070 patients (median age 66, IQR 54-75, 626 men) were included, of whom 536/1070 (50%) had a positive RT-PCR, 137/1070 (13%) patients were considered to have a possible or probable COVID- 19 based on the clinical reference standard. Chest CT yielded an AUC of 0.87 (95%CI 0.84-0.89) compared with RT-PCR and 0.87 (95%CI 0.85-0.89) compared with the clinical reference standard. A CO-RADS score ≥4 yielded an OR of 25.9 (95%CI 18.7-35.9) for a COVID-19 diagnosis by RT-PCR, and an OR of 30.6 (95%CI 21.1-44.4) by the clinical reference standard. For symptom duration of less than 48 hours, the AUC fell to 0.71 (95%CI 0.62-0.80; P<.001). CONCLUSION: Chest CT analysis using the COVID-19 reporting and data system (CO-RADS) enables rapid and reliable diagnosis of COVID-19, particularly when symptom duration is greater than 48 hours. See also the editorial by Elicker.