Changes in computed tomography findings of COVID-19 pneumonia: Less extensive lung involvement with decreasing disease prevalence.

It has been observed that the degree of pulmonary involvement shown in chest computed tomography (CT) scans tended to decrease as the prevalence of coronavirus disease 2019 (COVID-19) infection decreased in the Turkish population. The purpose of this study was to investigate the relationship between the disease severity based on chest CT scans and the temporal evolution of the epidemic. This study recruited 179 patients with confirmed COVID-19 disease who had received a chest CT scan between March 14 and April 28, 2020. The participants were divided into three successive temporal groups based on their date of CT examination. The early (March 14-29), mid (March 30-April 13), and late (April 14-28) groups were compared regarding the presence and extent of pulmonary involvement and CT characteristics of lesions. COVID-19 pneumonia was less extensive in participants under 45 years of age and patients presenting late in the course of epidemic (i.e., the late group) compared those presenting earlier. When each group was subcategorized on the basis of age, older patients in the late group had less extensive lung involvement than older patients in the early group. However, there was no significant difference in the extent of lung involvement in younger patients between the late and early groups. The severity of COVID-19 pneumonia appears to be variable at different temporal windows of the epidemic curve and decreases in patients presenting in the later weeks compared to the earlier weeks, particularly in older patients.

Preoperative computerized tomography screening for COVID-19 pneumonia in asymptomatic patients: experiences from two centers.

PURPOSE: The aim of this retrospective study is to evaluate the preoperative screening performance of chest CT (computerized tomography) examination to detect COVID-19 positive individuals. MATERIALS AND METHODS: In this retrospective study 218 adult patients who had preoperative chest CT and RT-PCR were enrolled. CT imaging results, which have been reported according to the Radiological Society of North America expert consensus on COVID-19, were collected from the picture archiving and communicating system. Demographic data, planned surgeries, and postoperative outcomes were collected from the electronic patient records. RESULTS: One patient (0.5%) showed typical CT features for COVID-19 pneumonia; 12 patients (5.5%) were reported as indeterminate, and eight (3.7%) were reported as atypical for COVID-19 pneumonia. Only one of the three patients with positive RT-PCR had abnormalities on CT. When RT-PCR tests were taken as reference, the sensitivity, specificity, and accuracy of chest CT in showing COVID-19 infection in asymptomatic patients were 33.3%, 90.7%, and 90.0%, respectively. CONCLUSION: Chest CT screening for COVID-19 has a very low yield in asymptomatic preoperative patients and shows false-positive findings in 9.2% of cases, potentially leading to unnecessary postponing of the surgery.