Radiological assessment of lung findings of cases during the COVID-19 (SARS-CoV-2) pandemic

Purpose: In this study, we aimed to investigate the presence and frequency of typical-atypical findings of the disease by grouping the thorax computed tomography (CT) examinations have been taken during the COVID-19 pandemic period according to American College of Radiology ACR, to help the diagnosis in the early period of the disease and to contribute to the early initiation of the treatment process by defining the typical findings. In addition, we aimed to evaluate the prognosis by examining the follow-up CT findings in the later stages of the disease. Material and Methods:In this study, patients who applied to Afyonkarahisar Health Sciences University Health Application and Research Center for various reasons between April 2020 and August 2020 during the COVID-19 pandemic, had thorax CT performed in the imaging unit of our hospital's Radiology Department and had RT-PCR (real-time polymerase chain reaction) test were included. During this period, patients who applied to our hospital and did not undergo thoracic CT examination or had external center imaging and did not receive the RT-PCR test were not included in our study. On the same date, the total leukocyte, lymphocyte, C-reactive protein (CRP), procalcitonin values and RT-PCR test results of the patients meeting the above-mentioned criteria were examined. Of the 600 patients included in the study, 300 were men and 300 were women. Age, gender, clinical and laboratory findings, comorbidities and mortality rates of patients in RT-PCR positive and RT-PCR negative groups, thoracic CT groups and characteristics according to ACR were analyzed comparatively. Mean and standard deviation were given in the descriptive statistics of continuous variables, and frequency (n) and percentage (%) values were given in the definition of categorical variables. Mann Whitney-U test was used to compare continuous variables that did not show normal distribution with two-level variables. Relationships between categorical variables were examined by Chi-square analysis. Results: In our study, the number of patients with positive RT-PCR test was 282 (47%), the number of patients with negative RT-PCR test was 318 (53%). While the RT-PCR test positivity rate was 51.6% in women, this rate was found as 42.3% in men. Although RT-PCR positivity rate was higher in females than males, it was not statistically significant (p> 0.05). Among the patients with positive RT-PCR, the highest number of patients was observed in group 3 (40-64 years). This rate was found to be 46%. The mortality rate in RT-PCR positive patients was 6.2%. The most frequently observed symptoms in patients with positive RT-PCR were cough (58%), myalgia (45%), fever (31%) and shortness of breath (30%). Myalgia and decreased taste and smell symptoms were found to be significantly higher in RT-PCR positive patients compared to RT-PCR negative patients. The most common laboratory findings were normal leukocyte, decreased lymphocyte, increased CRP and procalcitonin values. The most common accompanying comorbidities werehypertension (12%) and diabetes mellitus (10.6%). The most common thoracic CT category in the RT-PCR positive group was group 1 (classical pattern) which was observed in 61.7% of the patients. The most common CT density feature was a mixed pattern in which ground glass density and consolidation were observed together. Secondary CT findings were vascular enlargement, interlobular septal thickening, bronchial dilatation, fibrotic band and parallel pleural sign. Findings were bilateral, multifocal, peripheral and posterior dominant and showed a predominant distribution in the lower lobes. All these findings were found to be statistically significantly higher in RT-PCR positive patients compared to RT-PCR negative patients. Average time between first CT and follow-up CTs was 4.5 days. The most frequent pattern observed in follow-up CTs was progressive pattern. Conclusion: As a result, thorax CT plays an irreplaceable role in aiding diagnosis, assessing the severity of the disease and predicting prognosis during the pandemic period. Keywords: COVID-19, Thorax CT, American College of Radiology (ACR)