March 11, 2020
ACR Issues Recommendations on Chest Radiography and CT Use for Suspected COVID-19 Infection
March 11, 2020—The American College of Radiology (ACR) issued recommendations for the use of chest radiography and CT for suspected COVID-19 infection.
ACR advised that as COVID-19 spreads in the United States, there is growing interest in the role and appropriateness of chest radiographs and CT for the screening, diagnosis, and management of patients with suspected or known COVID-19 infection. Contributing to this interest are limited availability of viral testing kits to date, concern for test sensitivity from earlier reports in China, and the growing number of publications describing the chest radiographs and CT appearance in the setting of known or suspected COVID-infection.
To date, most of the radiologic data come from China. Some studies suggest that chest CT in particular may be positive in the setting of a negative test. ACR emphasized that knowledge of this new condition is rapidly evolving, and not all of the published and publicly available information is complete or up to date.
Key goals for the United States health care system in response to the COVID-19 outbreak are to reduce morbidity and mortality, minimize disease transmission, protect health care personnel, and preserve health care system functioning.
Based on concerns outlined below, the ACR recommends the following:
- CT should not be used to screen for COVID-19 or as a first-line test to diagnose COVID-19.
- CT should be used sparingly and be reserved for hospitalized symptomatic patients with specific clinical indications for CT. Appropriate infection control procedures should be followed before scanning subsequent patients.
- Facilities may consider deploying portable radiography units in ambulatory care facilities for use when chest radiographs are considered medically necessary. The surfaces of these machines can be easily cleaned, avoiding the need to bring patients into radiography rooms.
- Radiologists should familiarize themselves with the CT appearance of the COVID-19 infection to be able to identify findings consistent with infection in patients imaged for other reasons.
As summarized in the statement, the ACR believes that the following factors should be considered regarding the use of imaging for suspected or known COVID-19 infection:
- The Centers for Disease Control (CDC) does not currently recommend radiographs or CT to diagnose COVID-19. Viral testing remains the only specific method of diagnosis. Confirmation with the viral test is required, even if radiologic findings are suggestive of COVID-19 on chest radiographs or CT.
- For initial diagnostic testing for suspected COVID-19 infection, the CDC recommends collecting and testing specimens from the upper respiratory tract (nasopharyngeal and oropharyngeal swabs) or from the lower respiratory tract when available for viral testing.
- Generally, the findings on chest imaging in COVID-19 are not specific and overlap with other infections, including influenza, H1N1, SARS, and MERS. Being in the midst of the current flu season with a much higher prevalence of influenza in the United States than COVID-19 further limits the specificity of CT.
- The current ACR Appropriateness Criteria Statement on Acute Respiratory Illness, last updated in 2018, states that chest CT is “usually not appropriate.”
- A review from the Cochrane Database of Systematic Reviews on chest radiographs for acute lower respiratory tract infections (online here) concluded that chest radiographs did not improve clinical outcomes (duration of illness) for patients with lower respiratory tract infection; the review included two randomized trials comparing use of chest radiographs to no chest radiographs in acute lower respiratory tract infections for children and adults.
Additionally, there are issues related to infection control in health care facilities, including the use of imaging equipment:
- Primary care and other medical providers are attempting to limit visits of patients with suspected influenza or COVID-19 to health care facilities to minimize the risk of spreading infection. The CDC has also asked that patients and visitors to health care facilities be screened for symptoms of acute respiratory illness, be asked to wear a surgical mask, and be evaluated in a private room with the door closed.
- In addition to environmental cleaning and decontamination of rooms occupied by a patient with suspected or known COVID-19 infection by thorough cleaning of surfaces by someone wearing proper protective equipment, air flow within fixed radiography or CT scanner rooms should be considered before imaging the next patient. Ventilation is an important consideration for the control of airborne transmission in health care facilities (CDC guideline, online here). Depending on the air exchange rates, rooms may need to be unavailable for approximately 1 hour after imaging infected patients; air circulation rooms can be tested.
- These measures to eliminate contamination for subsequent patients may reduce access to imaging suites, potentially leading to substantial problems for patient care.
The complete ACR statement with links to additional resources is available here.