Coronavirus

COVID-19: New Guidelines Identify Best Imaging Modality for Detection

Chest computed tomography (CT) should be considered as a primary tool for detection of the 2019 novel coronavirus disease (COVID-19), according to new guidelines released by the Chinese government that were reiterated by the Radiological Society of North America (RSNA).1,2

The guidelines were issued following a study of 1014 patients in Wuhan, China, who underwent both chest CT scanning and reverse-transcription polymerase chain reaction (RT-PCR) tests. The performance of both tests was assessed, with RT-PCR as the reference standard. The study took place from January 6, 2020, to February 6, 2020.

Of the 1014 patients, 601 (59%) had RT-PCR findings that were positive for COVID-19, and 888 (88%) had chest CT scans that were positive for COVID-19. Other notable findings include:

  • Based on positive RT-PCR results, the sensitivity of chest CT scanning in suggesting COVID-19 was 97% (580 of 601 patients).
  • A total of 308 (75%) of 413 patients with negative RT-PCR results had positive chest CT findings. Of these 308 patients, 48% were considered as highly likely cases of COVID-19, and 33% were considered as probable cases.
  • The mean interval time between the initial negative to positive results of RT-PCR was 5.1 days, and the mean interval time between the initial positive to subsequent negative results of RT-PCR was 6.9 days.
  • Approximately 60% to 93% of cases had initial positive CT results consistent with COVID-19 prior (or parallel) to the initial positive results of RT-PCR.
  • Approximately 24 (42%) of 57 cases demonstrated improvement in follow-up chest CT scans before RT-PCR results had turned negative.


“Early diagnosis of [COVID-19] is crucial for disease treatment and control,” the authors of the study wrote. “Compared to RT-PCR, chest CT imaging may be a more reliable, practical, and rapid method to diagnose and assess COVID-19, especially in the epidemic area.”1

The RSNA echoed these sentiments in a press release: “In the absence of specific therapeutic drugs or vaccines for COVID-19, it is essential to detect the disease at an early stage and immediately isolate an infected patient from the healthy population.”2

—Christina Vogt

References:

  1. Ai T, Yang Z, Hou H, et al. Correlation of chest CT and RT-PCR testing in coronavirus disease 2019 (COVID-19) in China: a report of 1014 cases [published online February 26, 2020]. Radiology. https://doi.org/10.1148/radiol.2020200642.
  2. CT provides best diagnosis for COVID-19. News release. Radiological Society of North America. February 26, 2020. https://press.rsna.org/timssnet/media/pressreleases/14_pr_target.cfm?ID=2160.