Due to the nature of COVID-19 and the limited availability of viral testing kits, combined with concerns about their accuracy, some hospitals have taken to using chest X-ray or CT to assess patients with the virus. As the President of Radiology Services for Envision Physician Services, I would like to provide information and thoughts to our hospital partners on the role of chest CT and how its findings currently play in the management and diagnosis of COVID-19.
Can Chest CT and X-Ray Be Used to Diagnose COVID-19?
Due to the limited availability of viral testing kits, chest CT findings temporarily became part of the official diagnostic criteria of COVID-19. Last week, however, the American College of Radiology (ACR) recommended clinicians and health systems adhere to guidance published by the Centers for Disease Control and Prevention (CDC). Currently, the CDC does not recommend chest X-ray or chest CT as primary management tools for the diagnosis of COVID-19.
Why are Chest CT and X-Ray Not Considered Frontline Diagnosis Tools?
While chest CT and X-ray have been shown to identify patterns suggestive of viral infection, they have not proven reliable in ruling out COVID-19 infection. In general, the chest abnormalities seen with COVID-19 can overlap with those seen in a variety of other pulmonary infections and inflammatory processes, including influenza, H1N1 and SARS. According to the CDC, even if a chest CT or X-ray suggests COVID-19, viral testing is the only specific method for diagnosis.
Furthermore, up to 50 percent of patients with COVID-19 infection may have negative chest CT results at 0-2 days after the onset of flu-like symptoms.
Can Chest CT Help Confirm Presumed Cases of COVID-19?
In suspected cases awaiting the results of viral (RT-PCR) testing, patients are typically ordered to self-quarantine or are kept in isolation. In these situations, chest CT’s ability to confirm the presence of pulmonary disease would not provide a clear benefit for establishing a presumptive diagnosis.
Current testing for COVID-19 is considered to be relatively inaccurate. Because of the possibility of false-negative results, CT’s benefits are unclear, and scanning could possibly present infection control challenges in CT scan suites.
Some case reports have suggested that COVID-19 patients admitted to the ICU have more severe pulmonary consolidation on chest CT. Despite this, the available data is insufficient to recommend for or against serial chest CT as a prognostic tool to guide patient management in established cases.
There have been several articles published reflecting current guidelines and recommendations on the usefulness of CT in the diagnosis of COVID-19. Here is a selection of current literature:
Correlation of Chest CT and RT-PCR Testing in Coronavirus Disease 2019 (COVID-19) in China: A Report of 1014 Cases
Imaging Profile of the COVID-19 Infection: Radiologic Findings and Literature Review
CT Imaging Features of 2019 Novel Coronavirus (2019-nCoV)
With improved disease understanding and increased accuracy and rapidity of RT-PCR testing, CT is not considered to be a screening examination for COVID-19. Envision leadership understands that knowledge of this virus is rapidly evolving, however, and we will continue to share up-to-date information with our clinicians and hospital partners.
To access the most current and accurate information about COVID-19, visit www.envisionhealth.com/coronavirus.