Imaging for COVID-19
Jessica Mason, MD and Ali Raja, MD
- Chest x-rays have poor sensitivity and specificity overall in COVID-19.
- Chest x-rays are generally not needed in well appearing patients who are likely to be discharged.
- The sensitivity of chest x-ray for COVID ranges from 40-60%, and specificity ranges from 40-50%.
- The chest x-ray is helpful for hospitalized patients to establish a baseline at the time of admission.
- The expected chest x-ray findings in COVID is a multilobar, bilateral, ground glass opacity pattern and has a peripheral predominance.
- Single view AP chest films have become standard in many emergency departments to limit exposure of COVID patients to the radiology suite, which needs to be cleaned after imaging is complete.
- It is unclear if additional value is added with a lateral view.
- CT of the chest may be helpful in the appropriate scenario.
- If a CT is going to be ordered, a pulmonary angiogram is preferred, as this only changes the timing of contrast.
- A non-contrast CT adds little to the workup, but may have a niche role in a patient with a contrast allergy
- When to pursue a PE workup is a more challenging question.
- D-dimers tend to be elevated in COVID patients, and this test may be part of your institution’s admission labs.
- In a patient with dyspnea with an unresulted COVID test, if the chest x-ray looks relatively normal, consider a CT pulmonary angiogram.
- In this case, use the typical D-dimer threshold in decided whether or not to obtain a CT pulmonary angiogram.
- In a suspected COVID patient with a very high D-dimer (approximately 2,500 mg/L), consider a workup for pulmonary embolism.
- This is based on expert opinion and clear guidelines are currently unavailable.
- Anecdotally, pulmonary embolism is uncommon early in the course of illness.
- It is unclear if pulmonary emboli are due to COVID itself, or due to hospitalization and immobilization.
- Ultrasound can help make the diagnosis of COVID and be used for ongoing management.
- The ultrasound machine needs to be thoroughly cleaned after being used for a COVID patient.
- Ultrasound findings include:
- Irregular or thickened pleural lines
- B-lines
- Peripheral predominance
- Ultrasound is especially useful in low-resource settings.
- Ultrasound is also useful in the intensive care unit for:
- Evaluating the need and progress of recruitment maneuvers and prone positioning.
- Evaluating progression of illness.
- Imaging is useful when it changes the management of patients.
- Screening with CT was useful to better understand COVID early in the pandemic, but it is currently not recommended for screening patients or in mild cases.
- The COVID-19 chapter in CorePendium is frequently updated and contains multiple examples of the imaging findings referenced.
References:
https://pubmed.ncbi.nlm.nih.gov/32492712/
https://pubmed.ncbi.nlm.nih.gov/32907890/
https://pubmed.ncbi.nlm.nih.gov/32451823/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7233384/
ACEP Guideline:
https://www.acep.org/corona/COVID-19-alert/covid-19-articles/covid-19-ED-management-tool-now-available/
