In reply: Uncertainty in using chest computed tomography in early coronavirus disease (COVID-19).

To the Editor,

The recent letter by Drs Mungmunpuntipantipand Wiwanitkit1 argues that our report about chest computed tomography (CT) findings in a pregnant woman with coronavirus disease (COVID-19)2 are inconsistent with “early” COVID-19. In doing so, they discourage the consideration of CT findings when ruling out cases of COVID-19. Nevertheless, we think that their concern may have be guided by an incomplete understanding of the COVID-19 epidemic. As of 17 March 2020, more than 50,000 people have been confirmed with COVID-19 in Wuhan. During the period of the most severe increases in COVID-19 cases, the supply of nucleic acid detection kits could not meet the demands of the sharp increase in COVID-19 patients. So the diagnosis of COVID-19 followed the New Coronavirus Pneumonia Prevention and Control Program (fifthedition)1 issued by the National Health Commission of China that took “suspected cases with pneumonia imaging features” as the clinical diagnosis case standard in Hubei Province. This allowed more COVID-19 patients to receive more timely treatment.

In earlier stages of the disease progression, the changes of chest CT scan were mainly congestion, edema, and exudation. For example, Shi et al. reported that “COVID-19 manifests with chest CT imaging abnormalities, even in asymptomatic patients, with rapid evolution from focal unilateral to diffuse bilateral ground-glass opacities that progressed to or co-existed with consolidations”.3 It is worth noting that only a single ground-glass opacity can be seen in some patients at an early stage, and the range significantly increases in the short-term re-examination.4 When a patient’s condition improves, a few fibrous streaks may appear. On the contrary, when the condition is more advanced, diffuse lesions appear in the lungs, and the density of both lungs increases, showing a “white lung”, which seriously affects the patient’s lung function.4

Importantly, all diagnostic methods have disadvantages. In China, 29.2% of asymptomatic patients who were found to be infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and presented with either no or mild symptoms at the time of diagnosis by real-time reverse-transcriptionpolymerase chain reaction (RT-PCR) test had a normal chest CT scan.5 In addition, there were also some patients with positive chest CT findings who presented with a negative RT-PCR for SARS-CoV-2.6 Ai et al. showed that 60–93% of cases had an initial positive CT consistent with COVID-19 prior to (or parallel with) the initial positive RT-PCR results. Forty-two percent (24/57) of cases showed improvement in follow-up chest CT scans before the RT-PCR results turned negative.7 Thus, chest CT may still be considered as one of the primary tools for detecting COVID-19 in epidemic areas.

We therefore still suggest that the combined assessment of CT imaging features with clinical and laboratory findings could facilitate diagnosis of COVID-19 earlier and more accurately. This may also help curb the spread of the COVID-19 pandemic.