key: cord-0728322-ypxml3qr
authors: Khashoo, R.; Vimalesvaran, S.; Tewari, D.; Khashu, S.; Khashu, M.
title: Indiscriminate use of CT Chest Imaging during the COVID-19 Pandemic
date: 2022-01-31
journal: Clin Radiol
DOI: 10.1016/j.crad.2021.12.021
sha: 1417f5fbbb526abc110b349eba40648b1aa8e1f3
doc_id: 728322
cord_uid: ypxml3qr

nan

Dashboard) since the start of the pandemic, with a sharp increase between April to June 2021 2 . The extent of suffering seen in India as it dealt with the coronavirus pandemic shocked the world, whilst exposing weaknesses in the national healthcare infrastructure 2 . Although the chaos and horror of this pandemic continues to be heart wrenching, it has no doubt been heart-warming to see the laudable work performed by all healthcare and essential workers who have risen to the occasion and gone above and beyond their call of duty.

The lack of preparation on a global scale for the pandemic is obvious. The second wave in India and other countries has seen not only a shortage of intensive care beds, oxygen, drugs, and essentials, but also an increase in panic behaviour and unregulated prescriptions for antivirals, steroids, and a plethora of interventions that are not supported by evidence. One such intervention has been the use of computed J o u r n a l P r e -p r o o f tomography (CT) imaging of the chest at point-of-care for the diagnosis of SARS-CoV2 virus 3 . The reference standard test to confirm the diagnosis of COVID-19 is a reverse transcriptase polymerase chain reaction test 3 ; however, in many regions, practice has included indiscriminate use and reliance on chest CT images rather than molecular biology for diagnosis of COVID-19 as well for early prognostication, both of which are fraught with risks 3 .

In China, during the early phase of the outbreak, CT chest was widely used as a supporting tool in the diagnosis of COVID 19 4 ; however, current guidelines from 7 . The study found that in 28 countries, 80% of the healthcare centres conducted single-phase non-contrast chest CT, whereas multiphase chest CT examinations were performed in 20% of the centres in the remaining four countries. Other authors have also reported that there is little to no role of contrastenhanced CT images from multiphase scans in the diagnosis of COVID-19 7 . If a protocol, similar to that of a single-phase imaging, is used in each of the multiphase J o u r n a l P r e -p r o o f scans, additional phases would multiply the radiation dose delivered. They also reported there was an eightfold variation in median volumetric CT dose index, and a 10-fold variation in median dose-length product, which is a measure of CT tube radiation output/exposure. It should also be noted that many patients reported in this study also underwent multiple chest CT examinations in the 1-month duration. Some studies also suggest the usage of low-dose chest CT protocols, which did not lead to significant distortion of the final images, which would be achieved with general scan protocols 8 . The lowest median dose from the healthcare centres, surveyed by Homayounieh et al. was 4-5-times higher than that of the proposed low-dose protocols. Furthermore, this comparison shows that the low-dose chest CT protocols have not been widely adopted for COVID-19 patients. Only half of the healthcare facilities had a dedicated CT protocol for COVID-19 patients; however, the amount of the variability seen in these protocols in healthcare centres worldwide is considerable 6,7 .

Three main scenarios where imaging may be used as a primary diagnostic tool were identified in independent studies 3 : (1) patients with mild respiratory features consistent with COVID-19, but with risk factors for disease progression; (2) patients with moderate-to-severe features of COVID-19, regardless of RT-PCR test results; and (3) patients presenting with moderate-to-severe symptoms within a high prevalence of disease and with limited testing resources.

We wish to highlight that chest CT examinations are being done too early as a diagnostic test for COVID-19 in a large number of individuals who may not become unwell or require hospitalisation. Caution needs to applied when ruling out COVID-19 J o u r n a l P r e -p r o o f disease based on negative CT due to the high number of false negatives; especially when performed within 48 h of symptom onset . A recent study suggests that 5 days after the initial onset of symptoms, CT may be able to predict the patients who will later develop severe symptoms with 95% confidence 9 . If done too soon, it may be too early to see any lung changes, without significant value in prognostication of the disease process for the patient. Further to this, patients who then develop severe disease are subject to multiple CT examinations. The usual protocol followed in majority of hospitals in India and other countries surveyed 7 is that of high-resolution CT, depending upon the equipment and thickness of the section. On average a dose of 7 mSv is delivered, which is equal to the radiation absorbed from approximately

WHO declares COVID-19 a pandemic

Second wave of COVID-19 in India: dissection of the causes and lessons learnt

COVID-19 treatment guidelines: do they really reflect best medical practices to manage the pandemic?

Computed tomography chest in COVID-19: when & why?

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Variations in CT utilization, protocols, and radiation doses in COVID-19 pneumonia: results from 28 countries in the IAEA study

Managing radiation dose from chest CT in patients with COVID-19

Early prediction of severity in coronavirus disease (COVID-19) using quantitative CT imaging

Radiation risk from medical imaging

Chest CT for detecting COVID-19: a systematic review and meta-analysis of diagnostic accuracy