Catching the First Wave in the Pandemic: A Retrospective Evaluation of Chest CT Images for COVID-19

Pandemics generally begin in small areas and subsequently spread widely. In order to detect an outbreak in its early stage, observation of the data for small regions is important. The aim of this study to investigate the presence of COVID-19-like pneumonia findings in computed tomography (CT) taken before the COVID-19 pandemic in Turkey. The chest CTs performed in our hospital between December 1, 2019 and March 10, 2020 (study group) and those performed between December 1, 2018 and March 10, 2019 (control group) were retrospectively analyzed. A total of 1,432 chest CT images in the study group and 1,443 chest CT images in the control group were evaluated for COVID-19. The lesion characteristics on CT, length of hospital stay (LOS), and mortality rate were investigated. Typical lung involvement defined for COVID-19 was present in 1.39% (n=20/1,432) of CTs in the study group and 0.49% (n=7/1,443) in the control group (p=0.011). Seventy-five percent (n=15/20) of the study group were male, and the mean age of the patients was 51.8 (±17.1) years. All the patients in the study group had at least one of the symptoms of COVID-19, such as fever, cough, and respiratory distress. Ninety percent (n=18/20) of the patients in the study group had ground-glass opacities that showed a predominantly peripheral distribution. Five of these had accompanying consolidation and one had a reverse halo sign. According to clinical records, in-hospital mortality developed in seven of 20 patients (35%), the LOS was 5.5±6.2 days, and the median time from the symptom onset to admission was 4 (range: 1-12) days. Our study reveals that the onset of COVID-19 or a similar disease is more likely to occur earlier than first reported in the country.