Chest CT may help identify COVID-19 patients with initial negative lab tests

Leesburg, VA - Researchers have found in a new study that Chest CT is important in the screening of patients in whom disease is clinically suspected, especially those who have negative initial RT-PCR results.They further found that the less pulmonary consolidation on chest CT, the greater the possibility of negative initial RT-PCR results.

The findings of the study have been published in an open-access American Journal of Roentgenology (AJR).

One of the major concerns of the COVID-19 spread is asymptomatic silent spreaders. Another concern is the false negative antigen tests which can be troublesome for patients as well as medical professionals.

The researchers conducted a study to evaluate the diagnostic value of chest CT for coronavirus disease (COVID-19) pneumonia--especially for patients with negative initial results of reverse transcription-polymerase chain reaction (RT-PCR)testing.

From January 19 to February 20, 2020, lead investigator Dandan Chen of Guangzhou First People's Hospital in China obtained the admission data of 21 patients (nine men, 12 women; age range, 26-90 years) with confirmed COVID-19 pneumonia from five nonspecialized infectious disease hospitals across Guangzhou.

After undergoing chest CT and swab RT-PCR tests within 3 days, patients were divided into two groups: seven patients with negative initial results (who were found to have positive results after a second RT-PCR test 2 days later) and 14 patients with initial positive results.

"Most of the COVID-19 lesions were located in multiple lobes (67%) in both lungs (72%) in our study," Chen et al. wrote, adding that the CT findings observed most frequently were ground-glass opacities (95%) and consolidation (72%) with subpleural distribution (100%). "Otherwise," they continued, "33% of patients had other lesions around the bronchovascular bundle."

Additional chest CT findings identified by Chen and colleagues included air bronchogram (57%), vascular enlargement (67%), interlobular septal thickening (62%), and pleural effusions (19%).

Ultimately, compared with the positive initial RT-PCR results group, CT of the group with negative initial RT-PCR results was less likely to indicate pulmonary consolidation (p < 0.05).

Acknowledging that RT-PCR detection can be affected by laboratory reagents, test method, and subjective operability, Chen noted that, theoretically, the multicenter nature of this study--five hospitals in four districts of Guangzhou (13 cases in Huadu, four in Baiyun, three in Yuexiu, one in Nansha)--should have reduced interference by such factors.

"When patients with suspected COVID-19 pneumonia who have an epidemiologic history and typical CT features have negative initial RT-PCR results," the authors of this AJR article concluded, "repeated RT-PCR tests and patient isolation should be considered."

For more details click on the link: http://dx.doi.org/10.2214/AJR.20.23012