Optimal Imaging Modalities to Evaluate Pulmonary Status in Suspected COVID-19 Patients

Early diagnosis is important in treating any disease.

Optimal Imaging Modalities to Evaluate Pulmonary Status in Suspected COVID-19 Patients

Early diagnosis is important in treating any disease.

 

It is especially important in stopping the spread of COVID-19 and ensuring positive outcomes for patients in high-risk categories. Imaging has played a role in diagnosing and monitoring acute respiratory diseases for many years, and it continues to be vital in screening, assessing, and diagnosing COVID-19. Many imaging modalities may be used to great efficacy, but they should be applied to patient care only within a larger-perspective strategy of care. This is true when considering chest x-ray, ultrasound, CT, and SPECT.

Screening and diagnosis of COVID-19 is constantly evolving. At the time of publication, RT-PCR (real-time reverse transcriptase-polymerase chain reaction) is the primary means of diagnosis in the United States. RT-PCR has high specificity (95–97%) but only moderate sensitivity (60–70%) (Hauimi et al., 2020). This moderate sensitivity has been an issue with current tests, as it is plagued by false negatives (USDA, 2020).

Computed Tomography

CT emerged early as an option for diagnosing and monitoring of COVID-19 cases, but the American College of Radiology (ACR) has recently cautioned against its use as a frontline diagnostic tool. Because there is cause for concern regarding potential selection bias in these studies (ACR, 2020), more review will be necessary before CT is moved into a primary screening role. The current guidelines provided by the ACR state CT should be used to monitor complications within COVID-19 patients (ACR, 2020). Among the problems are contamination of rooms (increasing turnover time because of additional cleaning procedures that make the equipment unavailable for other patient use), increased exposure of staff, and patient exposure to increased doses of radiation inherent with the use of CT (RadiologyInfo.org, 2019).

Ultrasound

Studies focusing on the use of lung ultrasound have exhibited early promising results, which have made it the frontrunner in imaging COVID-19 cases. Lung ultrasound has the advantages of being radiation-free, mobile, and already widely available (Peng et al., 2020). With recent developments in hand-held mobile point of care ultrasound technologies, this is an attractive option for initial lung evaluation. Point of care ultrasound technology has many uses in diagnosing and treating suspected or confirmed COVID-19 patients, with applicability for cardiac evaluations/echocardiograms and for vascular evaluations, specifically venous assessment for deep vein thrombosis.

Check out our Executive Summary Report on the use of Point of Care Ultrasound in COVID-19 for information on vendors, technical specifications, clinical evidence, and operational considerations for integrating into care delivery.

Diagnostic X-Ray

This is a traditional first-line evaluation of the lungs, offering cost-effective screening and mobile technology. Though the radiation exposure is magnitudes less than with CT (0.1 mSv for x-ray vs 7 mSv for CT), there is still a risk of exposure to radiation with this evaluation method (RadiologyInfo.org, 2019). Portable x-rays excel at Anteroposterior (AP) views of the chest and are used for quickly evaluating lungs in a variety of hospital settings (from the ED to the ICU). These machines are already widely available in hospitals. While it is possible to miss pneumonia in early stages (Hauimi et al., 2020), x-rays have the advantages of speed of exam and low radiation dose. Thus, this test may be repeated multiple times over the course of a few days before reaching the radiation threshold of CT.

To date, there are no clinical studies evaluating SPECT for screening and diagnosing COVID-19.

References

American College of Radiology. ACR recommendations for the use of chest radiography and computed tomography (CT) for suspected COVID-19 infection. (2020, March 11). Home | American College of Radiology.

Hauimi, A. et al., (2020). COVID-19. Radiopaedia. Retrieved April 24, 2020.  

Peng, Q., Wang, X., & Zhang, L. (2020). Findings of lung ultrasonography of novel corona virus pneumonia during the 2019–2020 epidemic. Intensive Care Medicine. 

RadiologyInfo.org. Radiation Dose in X-Ray and CT Exams (2019).  Retrieved April 27, 2020.

The Radiology Assistant (2020). COVID-19. Retrieved April 27, 2020.  

U.S. Food and Drug Administration (2020). Accelerated emergency use authorization (EUA) summary COVID-19 RT-PCR test (Laboratory Corporation of America). Retrieved April 27, 2020.

Author:

Camille A. Allred, MSRS R.T.(R) (ARRT)

Clinical Analyst

Camille joined TractManager in 2020 as a clinical analyst specializing in cardiac and interventional imaging solutions.

 

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