Structured reporting in portable chest radiographs: An essential tool in the diagnosis of COVID-19

Abstract

Purpose: To date, the majority of chest imaging studies in COVID-19 pneumonia have focused on CT. Evidence for the utility of chest radiographs (CXRs) in this population is less robust. Our objectives were to develop a systematic approach for reporting likelihood of COVID-19 pneumonia on CXRs, to measure the interobserver variability of this approach and to evaluate the diagnostic performance of CXRs compared to real-time reverse transcription polymerase chain reaction (RT-PCR).

Method: Retrospective review of patients suspected of having COVID-19 pneumonia who attended our emergency department and underwent both CXR and a RT-PCR were included. Two radiologists reviewed the CXRs, blind to the RT-PCR, and classified them according to a structured reporting template with five categories (Characteristic, High Suspicion, Indeterminate, Unlikely and Normal) which we devised. For analysis of diagnostic accuracy, Characteristic and High Suspicion CXRs were considered positive and the remaining categories negative. Concordance between the two assessors was also measured.

Results: Of 582 patients (51 +/- 20 years), 143/582 (24.6 %) had a positive RT-PCR. The absolute concordance between the two assessors was 71.1 % (414/582) with a Fleiss-Cohen-weighted Cohen's κ of 0.81 (95 % confidence interval, 0.78-0.85). A patient with a positive CXR had an 88 % (95 % CI 80-96 %) probability of having a positive RT-PCR during a period of high incidence, early in the COVID-19 pandemic.

Conclusion: Using a structured approach, a positive CXR had a high likelihood of predicting a positive RT-PCR, with good interrater reliability. CXRs can be useful in identifying new cases of COVID-19.

Keywords: COVID-19; Diagnostic imaging; Radiology.

Fig. 1

CXR Structured Assessment: COVID-19.

Fig. 2

An example of a Characteristic chest radiograph (CXR). 60 year old man presented to the emergency department with a history of cough, dyspnoea and pleuritic chest pain. On the baseline CXR there were bilateral subpleural opacities that were relatively symmetrical and of large volume consistent with a Characteristic CXR. Real-time reverse transcription polymerase chain reaction RT-PCR of a swab taken on the same day as the CXR was positive for COVID-19.

Fig. 3

An example of a High Suspicion chest radiograph (CXR). 79 year old man presented to the emergency department with a history of cough and dyspnoea. On the CXR there were bilateral large volume patchy opacities consistent with a High Suspicion CXR. Real-time reverse transcription polymerase chain reaction RT-PCR of a swab taken on the same day was positive for COVID-19.

Fig. 4

An example of an Indeterminate chest radiograph (CXR). 71 year old woman presenting with increasing dyspnoea on a background of chronic obstructive pulmonary disease. On CXR there were unilateral large volume, multilobar opacities consistent with an Indeterminate CXR. Real-time reverse transcription polymerase chain reaction RT-PCR of a swab taken on the same day was negative for COVID-19.

Fig. 5

An example of an Unlikely chest radiograph (CXR). A 44 year old woman presented to the emergency department with cough, dyspnoea and left side pleuritic chest pain. On CXR there was dense consolidation throughout the left lower lobe consistent with a lobar pneumonia pattern. This was classified as an Unlikely CXR. Reverse transcription polymerase chain reaction RT-PCR of a swab taken on the same day was negative for COVID-19.