Accuracy and Reproducibility of Low-Dose Submillisievert Chest CT for the Diagnosis of COVID-19

Abstract

To demonstrate the accuracy and reproducibility of low-dose submillisievert chest CT for the diagnosis of coronavirus disease 2019 infection in patients in the emergency department. Materials and Methods:This was a Health Insurance Portability and Accountability Act-compliant, institutional review board-approved retrospective study. From March 14 to 24, 2020, 192 patients in the emergency department with symptoms suggestive of COVID-19 infection were studied by using low-dose chest CT and real-time reverse transcription polymerase chain reaction (RT-PCR). Image analysis included the likelihood of COVID-19 infection and the semiquantitative extent of lung involvement. CT images were analyzed by two radiologists blinded to the RT-PCR results. Reproducibility was assessed using the McNemar test and intraclass correlation coefficient. Time between CT acquisition and report was measured.Results: When compared with RT-PCR, low-dose submillisievert chest CT demonstrated excellent sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for diagnosis of COVID-19 (86.7%, 93.6%, 91.1%, 90.3%, and 90.2%, respectively), in particular in patients with clinical symptoms for more than 48 hours (95.6%, 93.2%, 91.5%, 96.5%, and 94.4%, respectively). In patients with a positive CT result, the likelihood of disease increased from 43.2% (pretest probability) to 91.1% or 91.4% (posttest probability), while in patients with a negative CT result, the likelihood of disease decreased to 9.6% or 3.7% for all patients or those with clinical symptoms for .48 hours. The prevalence of alternative diagnoses based on chest CT in patients without COVID-19 infection was 17.6%. The mean effective radiation dose was 0.56 mSv 6 0.25 (standard deviation). Median time between CT acquisition and report was 25 minutes (interquartile range: 13-49 minutes). Intra-and interreader reproducibility of CT was excellent (all intraclass correlation coefficients  0.95) without significant bias in the Bland-Altman analysis. Conclusion:Low-dose submillisievert chest CT allows for rapid, accurate, and reproducible assessment of COVID-19 infection in patients in the emergency department, in particular in patients with symptoms lasting longer than 48 hours. Chest CT has the additional advantage of offering alternative diagnoses in a significant subset of patients.

Chest CT features of the novel coronavirus disease (COVID-19)

“…Exposure to medical radiation is a concern in patients with suspected or diagnosed COVID-19 pneumonia, especially in infants, children, young adults, and pregnant patients. Therefore, it is necessary to prevent or reduce radiation exposure [6,7,20,54]. First, it should be distinguished appropriately in which patients need imaging and in which patient imaging is not needed.…”

“…Second, chest CT should be obtained as low as possible radiation dose in cases with CT indication. Dangis et al [54] showed that chest CT with low-dose settings would provide the diagnosis of COVID-19 pneumonia with similar accuracy as standard-dose chest CT.…”

Low-dose CT in COVID-19 outbreak: radiation safety, image wisely, and image gently pledge

“…1 and 2). In a retrospective study [13], LDCT with iterative reconstruction (IR) demonstrated sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of about 90% in the diagnosis of COVID-19. These parameters further increased to up to 96% when patients were symptomatic for more than 48 h. The likelihood of COVID-19 diagnosis increased to 91% from pre-LDCT value of 43% in patients with suggestive imaging findings whereas it was decreased to 9% in those with normal or atypical imaging findings.…”

“…both young and elderly [12]. Since there is currently no vaccine for COVID-19, successful disease containment is contingent upon rapid identification of infected individuals to isolate them and their close contacts [9,13]. The urgent need for an alternative diagnostic than RT-PCR kits has given rise to the possibility of utilization of chest CT findings as a diagnostic aid and a screening tool in suspected patients [13].…”

“…Bilateral ground-glass opacities (GGO) and/or consolidation have been suggested as the hallmark of COVID-19 infection on chest CT images [7,9,[13][14][15]. While they may be nonspecific, these findings are easily identifiable on CT and should in the proper clinical setting aid diagnosis.…”