Unenhanced computed tomography (CT) utility for triage at the emergency department during COVID-19 pandemic

Abstract

Background Unenhanced chest computed tomography (CT) can assist in the diagnosis and classification of coronavirus disease 2019 (COVID-19), complementing to the reverse-transcription polymerase chain reaction (RT-PCR) tests; the performance of which has yet to be validated in emergency department (ED) setting. The study sought to evaluate the diagnostic performance of chest CT in the diagnosis and management of COVID-19 in ED. Methods This retrospective single-center study included 155 patients in ED who underwent both RT-PCR and chest CT for suspected COVID-19 from March 1st to April 1st, 2020. The clinical information, CT images and laboratory reports were reviewed and the performance of CT was assessed, using the RT-PCR as standard reference. Moreover, an adjudication committee retrospectively rated the probability of COVID-19 before and after the CT calculating the net reclassification improvement (NRI). Their final diagnosis was considered as reference. The proportion of patients with negative RT-PCR test that was directed to the referent hospital based on positive CT findings was also assessed. Results Among 155 patients, 42% had positive RT-PCR results, and 46% had positive CT findings. Chest CT showed a sensitivity of 84.6%, a specificity of 80.0% and a diagnostic accuracy of 81.9% in suggesting COVID-19 with RT-PCR as reference. Concurrently, corresponding values of 89.4%, 84.3% and 86.5% were retrieved with the adjudication committee diagnosis as reference. For the subgroup of patients with age > 65, specificity and sensitivity were 50% and 80.8%, respectively. In patients with negative RT-PCR results, 20% (18/90) had positive chest CT finding and 22% (4/18) of those were eventually considered as COVID-19 positive according to the adjudication committee. After CT, the estimated probability of COVID-19 changed in 10/104 (11%) patients with available data: 4 (4%) were downgraded, 6 (6%) upgraded. The NRI was 1.92% (NRI event −2.08% + NRI non-event 5.36%). No patient with negative RT-PCR but positive CT was eventually directed to hospital. Conclusion Chest CT showed promising sensitivity for diagnosing COVID-19 across all patients' subgroups. However, CT did not modify the estimated probability of COVID-19 infection in a substantial proportion of patients and its utility as an emergency department triage tool warrants further analyses.

Evaluating tests for diagnosing COVID-19 in the absence of a reliable reference standard: pitfalls and potential solutions

“…An example of such an adjudication committee is reported in a study where five board-certified specialists in respiratory and internal medicine were retrospectively invited to make a final diagnosis for each patient suspected of COVID-19. [30] In a similar study, all patients with a positive chest CT, but a negative RT-PCR, were discussed in a multidisciplinary meeting to arrive at a final diagnosis. [31] Panel-based diagnosis has the advantage of reflecting clinical settings, where it is common practice that difficult cases are examined during multidisciplinary meetings.…”

COVID-19 diagnostic approaches with an extensive focus on computed tomography in accurate diagnosis, prognosis, staging, and follow-up

“…During chronic lung inflammation, the activity of neutrophils exclusively relies on anaerobic glycolysis, leading to increased glucose consumption and the uptake of FDG. Also, granulocytes and macrophages effectively facilitate glucose transport under chronic inflammatory conditions [67,68]. Amini et al reported a case of an 82-year-old man with a history of colon cancer, who complained of myalgia and fatigue for 10 days.…”

A Pictorial Review of the Role of Imaging in the Detection, Management, Histopathological Correlations, and Complications of COVID-19 Pneumonia

“…Chest CT, due to its high sensitivity and widespread availability, is considered to be an effective tool to support the diagnosis of COVID-19 pneumonia with high or intermediate clinical probability, since it allows a rapid diagnostic workflow in emergency triage and may partially overcome the long turnaround time of RT-PCR [ 11 , 94 , 95 , 96 , 97 , 98 , 99 ]. In the emergency setting, patients with CT findings typical of COVID-19 pneumonia can be promptly isolated.…”

“…In the emergency setting, patients with CT findings typical of COVID-19 pneumonia can be promptly isolated. However, a study by Skalidis et al [ 97 ] showed that CT did not modify the estimated probability of COVID-19 infection and RT-PCR testing is generally required to confirm the diagnosis [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 22 , 23 ]. With the use of RT-PCR as the gold standard tool, chest CT usually showed greater than 90% sensitivity, with low to moderate specificity values ranging between 25 and 56% [ 8 , 100 ].…”