Objective To evaluate and compare the diagnostic values of CT findings and nucleic acid testing in the corona virus disease 2019 (COVID-19) and investigate their features in the disease course.

Methods The retrospective analysis was performed on the data of patients who received chest CT and nucleic acid testing from January 20, 2020 to March 5, 2020 in the First Affiliated Hospital of Zhengzhou University. This study involved 164 patients, including 76 confirmed (40 males and 36 females, aged 25−83 years old) and 88 suspected (47 males and 41 females, aged 21−75 years old) cases. The patients were divided into <60 years old group (122 cases) and ≥60 years old group (42 cases). The performance of CT in diagnosing COVID-19 was assessed using nucleic acid testing results as the gold standard. For confirmed patients with multiple CT images and nucleic acid tests, the CT findings and nucleic acid testing results were analyzed comparatively from the beginning of the disease to the progress and turnover of the disease.

Results Of 164 patients, 46.3% (76/164) had positive nucleic acid testing results, and 87.2% (143/164) had positive CT findings. Considering the nucleic acid testing results as standard, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of CT in diagnosing COVID-19 were 96.1% (73/76), 20.5% (18/88), 51.0% (73/143), 85.7% (18/21), and 55.5% (91/164), respectively. There was no significant difference in CT diagnostic efficiency between <60 years old group and ≥60 years old group (χ²=0.051−0.414, all P>0.05). In patients with negative nucleic acid testing results, 79.5% (70/88) had positive CT findings. In patients with positive nucleic acid testing results, 10.5% (8/76) had no symptom, 9.2% (7/76) had negative CT findings, and 14.5% (11/76) had negative nucleic acid testing results when first examined. Among the 11 patients with initially negative nucleic acid testing results, 81.8% (9/11) had positive CT findings, and the nucleic acid testing results changed from negative to positive during the follow-up period. In the course of disease development, the CT could present progress and improvement. The nucleic acid testing results of 50.0% (14/28) of cases with CT finding improvement changed from positive to negative in the follow-up at 4 to 8 days, and the nucleic acid testing results of 67.4% (31/46) cases changed from positive to negative in the follow-up at 9 to 12 days.

Conclusion CT had higher sensitivity for the diagnosis of COVID-19 compared with the initial nucleic acid testing and could show condition improvement earlier than the nucleic acid testing results, it is an important supporting means in clinical practice .