key: cord-1011802-ygqin14x
authors: Stevens, Barry J.
title: Reporting radiographers’ interpretation and use of the British Society of Thoracic Imaging’s coding system when reporting COVID-19 chest x-rays
date: 2020-06-18
journal: Radiography (Lond)
DOI: 10.1016/j.radi.2020.06.010
sha: 136b17ab143c46f3268506b0d216c55ff44efb7f
doc_id: 1011802
cord_uid: ygqin14x

Abstract Introduction The United Kingdom (UK) has experienced one of the worst initial waves of the COVID-19 pandemic. Clinical signs help guide initial diagnosis, though definitive diagnosis is made using the laboratory technique reverse transcription polymerase chain reaction (RT-PCR). The chest x-ray (CXR) is used as the primary imaging investigation in the United Kingdom (UK) for patients with suspected COVID-19. In some hospitals these CXRs may be reported by a radiographer. Methodology Retrospective review of CXR reports by radiographers for suspected COVID-19 patients attending the Emergency Department (ED) of a hospital in the UK. Interpretation and use of the British Society of Thoracic Imaging (BSTI) coding system was assessed. Report description and code use were cross-checked. Report and code usage were checked against the RT-PCR result to determine accuracy. Report availability was checked against the availability of the RT-PCR result. A confusion matrix was utilised to determine performance. The data were analysed manually using Excel. Results Sample size was 320 patients; 54.1% male patients (n = 173), 45.9% female patients (n = 147). The correct code matched report descriptions in 316 of the 320 cases (98.8%). In 299 of the 320 cases (93.4%), the reports were available before the RT-PCR swab result. CXR sensitivity for detecting COVID-19 was 85% compared to 93% for the initial RT-PCR. Conclusion Reporting radiographers can adequately utilise and apply the BSTI classification system when reporting COVID-19 CXRs. They can recognise the classic CXR appearances of COVID-19 and those with normal appearances. Future best practice includes checking laboratory results when reporting CXRs with ambiguous appearances. Implications for practice Utilisation of reporting radiographers to report CXRs in any future respiratory pandemic should be considered a service-enabling development.

The United Kingdom (UK) has experienced one of the worst initial waves of the COVID-19 pandemic. Clinical signs help guide initial diagnosis, though definitive diagnosis is made using the laboratory technique reverse transcription polymerase chain reaction (RT-PCR). The chest x-ray (CXR) is used as the primary imaging investigation in the United Kingdom (UK) for patients with suspected COVID-19. In some hospitals these CXRs may be reported by a radiographer.

Retrospective review of CXR reports by radiographers for suspected patients attending the Emergency Department (ED) of a hospital in the UK.

Interpretation and use of the British Society of Thoracic Imaging (BSTI) coding system was assessed. Report description and code use were cross-checked.

Report and code usage were checked against the RT-PCR result to determine accuracy. Report availability was checked against the availability of the RT-PCR result. A confusion matrix was utilised to determine performance. The data were analysed manually using Excel.

The United Kingdom (UK) has experienced one of the worst initial waves of the COVID-19 coronavirus pandemic, which originated in Wuhan, China, in December 2019. At the time of writing, in the UK there have been over 290,000 positive cases and over 41,000 fatalities 1 . The Midlands region has the second highest prevalence of the disease in the UK, second behind London 2 .

Common clinical signs and symptoms help guide clinicians' initial diagnosis. The definitive diagnosis is typically made using the laboratory technique reverse transcription polymerase chain reaction (RT-PCR) from a nasal and pharyngeal swab; though, the positivity rates of RT-PCR specimens from these sites is reportedly only 32% and 63%, respectively 3 . Consequently, several tests may be undertaken before a positive RT-PCR result is achieved. A recent meta-analysis 4 describes blood tests that may also manifest as positive indicators of COVID-19, such as lymphopenia, raised C-reactive protein (CRP), and hypoalbuminemia.

The blood results are usually interpreted in conjunction with various other tests, including findings from a chest x-ray (CXR).

The CXR is the initial imaging investigation for all patients in which COVID-19 is suspected 5 , or patients with mild features of COVID-19 at risk for disease progression and patients with worsening respiratory status 6 . The CXR reportedly has lower sensitivity in early or mild cases when compared with the RT-PCR 7 ;

with one study reporting 69% sensitivity 8 . The CXR report may be available to clinicians before the RT-PCR result. Therefore, an accurate chest x-ray interpretation is paramount in helping to guide the early diagnosis and treatment plan. It is suggested that positive CXR findings in patients with high suspicion of COVID-19 can negate the need for a Computed Tomography (CT) scan 9 . CT scanning was used in China as the primary modality for investigating COVID-19 10 . In the UK however, CT scanning is reserved for seriously ill patients 11 .

Considering the logistical and infection control issues associated with transporting COVID-19 patients to the CT scanner; utilising the CXR appropriately could help maintain uninterrupted inpatient throughput in CT departments.

Departmental workloads may well be reduced during the COVID-19 pandemic due to the postponement of routine examinations from outpatient clinics and general practitioner referrals. Though, it is possible that Radiologists will still be engaged with reporting CT and Magnetic Resonance Imaging (MRI) reporting backlogs rather than be concerned with reporting Emergency Department (ED) 

This study was a retrospective review of ED chest x-ray reports authored by three Reporting Radiographers in a National Health Service (NHS) district general hospital in the West Midlands region of the UK. The Health Research Authority tool 18 deemed this review to be a service evaluation, so ethical approval was not required. Authorisation to proceed was granted by the local Imaging Quality Team.

The review covered examinations spanning 45 days from 17 th March to 30 th April 2020. The criteria for inclusion were; adult patients attending the ED with the diagnostic question querying COVID-19, with a BSTI code in the report and an initial RT-PCR swab result. A Radiology Information System (RIS) search was undertaken to include the reports by radiographers and the inclusion criteria.

The sample did not represent all patients who were diagnosed with COVID-19 at the Trust during this period, and it did not include any CXRs reported by

Radiologists. The decision tree in figure 1 illustrates how the sample was determined. Figure 1 : A decision tree illustrating how the cases in the sample were selected using the described inclusion criteria.

The RT-PCR result was used as a standard to benchmark the reports and codes against. Each report was analysed to primarily assess if the report description Radiographers, a Radiologist was asked to provide their interpretation as the arbiter. The process of reviewing these cases was to state whether they perceived the appearances to be in keeping with COVID-19 or not.

The sample comprised of 320 cases, consisting of 54.1% male patients (n = 173) and 45.9% female patients (n = 147). The mean age of patients was 67.1 years (standard deviation 17.5, minimum 21, maximum 100), the median age was 70 years and the mode was 82 years.

The Reporting Radiographers used the correct code to match their report description in 316 of the 320 cases (98.8%). In 299 of the 320 cases (93.4%), the reports were available for the clinicians before the RT-PCR swab result.

Of the 47 cases reported with this code, 29 (62%) were correctly reported as normal and 18 (38%) were proven to be positive by an initial RT-PCR swab. The 18 false negative cases were independently and blindly reviewed by the Reporting Radiographers, in five cases the reviews of the Reporting Radiographers were discordant, and these were reviewed by the arbiter Consultant Radiologist. The consensus being that all cases that were reported as normal were correctly identified as having no radiographic features of COVID-19.

Of the 18 false negative cases, 15 had raised CRP, 11 had lymphopenia and 3

had decreased albumin; only three cases had a full complement of these features. Eighty-three percent (n = 39/47) of these reports were available before the RT-PCR result.

Of the 160 cases with this code, 123 (77%) identified COVID-19 correctly when correlated with the RT-PCR result, and 37 (23%) were proven to be negative by the initial RT-PCR. However, almost a third of the cases that had a negative initial RT-PCR result went on to have a subsequent positive result (n = 11/37, 30% 

Of the 82 cases reported with this code, 57 (70%) identified COVID-19 correctly 

Of the 31 cases with this code, 18 (58%) were correctly reported as non-COVID- 

Normal appearances -wrong code 2 COPD, one case with pleural effusion 1

Pulmonary oedema 1

Lobar pneumonia 1 COVID-19 appearances -wrong code 1

Unilateral basal consolidation 

The findings from this review suggest that a reporting radiographer-led CXR hot reporting service using a recognised coding system can be effective in a pandemic situation. The hot reporting service offered during normal hours, with reduced service at the weekend, ensured that the large majority of reports were available before the RT-PCR result. The cases with reports correctly describing positive COVID-19 features would likely have aided the referrer in managing the patient appropriately, prior to confirmation by RT-PCR. There was only a small amount of incorrect code use (n = 3/320, 0.9%) or misinterpretation of findings (n = 16, 5%), considered to be within acceptable tolerances as documented in the literature 19, 20 .

With the RT-PCR results as a gold standard; the agreement of the initial RT-PCR test and CXR in determining presence of COVID-19 was 94% and 85%, respectively. The sensitivity of the CXR prior to, and following, the described adjustments was 85.3% and 94.4%, respectively, and are superior to previous work by Wong et al. 8 , which reported 69% CXR sensitivity. In view of this, the CXR can be considered to have been a useful tool in the preliminary screening of patients in this sample.

The fact that the reporting team and Radiologist arbiter reached agreement that the 18 false negative reports with code CVCX0 all had normal appearances, despite returning a positive RT-PCR result, corroborates findings from previous work suggesting that there may be no radiographic features in early or mild disease 7,10,21 .

The CXR features in 10 of 13 false negative reports with code CVCX3, categorised these cases as non-COVID-19 as guided by the BSTI proforma.

Yet, they had a positive RT-PCR result. It is interesting that the existence of pleural fluid, for example, does not necessarily exclude the presence of COVID-19, having been previously reported as being present in severe cases 22 They compared CT reports to RT-PCR results and suggest that some of the "false-positive" cases on CT may be "true-positive" in view of the imperfect reference standard of the RT-PCR. Considering the 60% of cases in this sample with a false positive report that did not have a repeat RT-PCR swab and the subsequent positivity rate for those that did, along with understanding of the issues associated with RT-PCR testing, it is possible that the actual initial sensitivity of the CXR report could be higher than it appears. Furthermore, it is argued that sequential RT-PCR swabs should be undertaken in cases with CXR findings suspicious of COVID-19 6 . It is also possible that the swab collection of these patients occurred at an inappropriate time relative to disease onset considering the positivity rate of nasopharyngeal RT-PCR declines rapidly after one week of symptom onset 3 .

The distribution of mortality by age in this sample follows the national trend in that the majority of fatalities are seen in the 80+ years old category 2 . However, the presence of any underlying comorbidities among the fatalities has not been investigated here, but this does provide scope for further investigation.

The retrospective nature of this study needs to be appreciated. The potential effects of confirmation bias need to be recognised when interpreting the findings from this review, as previously mentioned. During the process of blindly reviewing the cases that were discordant with the RT-PCR result, the reporting radiographers were not exempt from potentially reviewing a case that they may have previously reported. This introduces the effect of recall bias whereby the individual may remember the image findings and their original report, thus possibly rendering their review to be subjective rather than objective.

The findings from this retrospective review indicate that Reporting Radiographers can adequately utilise and apply the BSTI classification system when reporting COVID-19 CXRs. Reporting Radiographers can accurately recognise the classic CXR appearances of COVID-19, as described by the BSTI, and those with normal appearances. In the cases with ambiguous or non-classic COVID-19 appearances, it would be worthwhile to correlate imaging findings with laboratory results when compiling the report. Utilisation of Reporting

Radiographers to report CXRs in any future respiratory pandemics should be considered as a service-enabling development.

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