A British Society of Thoracic Imaging statement: considerations in designing local imaging diagnostic algorithms for the COVID-19 pandemic.

In accordance with guidance from the Chief Medical Officer's office and the Royal College of Radiologists, the British Society of Thoracic Imaging (BSTI) recognises that based on the available evidence computed tomography (CT) currently has no upfront role in the diagnostic work-up of 2019 novel coronavirus (COVID-19) infection (https://www.rcr.ac.uk/college/coronavirus-covid-19-what-rcr-doing/rcr-position-role-ct-patients-suspected-covid-19). Nevertheless, a number of reports have been published highlighting CT appearances in COVID-19, raising the possibility of a role for CT in patient management.1, 2, 3, 4, 5 In response to these reports, the BSTI published a preliminary consensus statement on 6 March 2020.6 We discuss below what role, if any, CT would play in the detection and management of COVID-19 infection in the UK, and the logistics of imaging delivery. This role is heavily predicated on the clinical context as well as the timing of its intended use within the diagnostic pathway, especially relative to the current reference standard diagnostic test, real-time reverse transcriptase polymerase chain reaction (RT-PCR) of a pharyngeal swab,7 and other clinical and laboratory investigations. Although it may not be feasible or desirable for isolation purposes to perform a chest radiograph (CXR), we should acknowledge that pragmatically patients with a respiratory complaint are likely to present via any number of routes (primary care, emergency departments [EDs] or outpatient clinics) having already had a CXR, other than to isolation pods outside a hospital, and work-up of a respiratory complaint would usually include a CXR in such settings. Cognizant of this fact, in the following discussion we have considered how a CXR would also fit into diagnostic algorithms, and in particular, how the use of CT would alter management in settings where a CXR was or was not available. As such, we deliberate the following questions: (1) would a CT thorax contribute to management of symptomatic cases after a rapidly available RT-PCR result? (2) Would a CT thorax contribute to symptomatic cases if an RT-PCR test was not available or had to be rationed, and (a) a chest radiograph had been performed and was abnormal? (b) A chest radiograph had been performed and was normal, or was not/could not be performed? (3) Would a CT thorax contribute to the detection and management of COVID-19 in asymptomatic high-risk cases? (4) How should imaging (CT thorax or CXR) be provided? (5) What would a COVID-19 diagnostic algorithm look like? In the following discussion, a high pre-test probability is assumed for symptomatic cases, based on one or more of: clinical presentation (Pyrexia of 37.8); acute onset persistent cough, hoarseness, nasal discharge or congestion, shortness of breath, sore throat, wheezing, sneezing; and compatible laboratory abnormalities (relative lymphopenia, elevated C-reactive protein [CRP]).8