The prevalence of single pulmonary nodules as the first sign of COVID-19 pneumonia in CT scans of patients suspected to COVID-19

Background: The role of diffuse nodular lesions has been cited as a specific indication for COVID-19 progresiion and severity; however the place of single nodules in this role is quite ambiguous. The present study aimed to determine the prevalence of single pulmonary nodules as the first sign of COVID-19 pneumonia in CT scans of patients suspected to disease. Methods: In this cross-sectional study, all consecutive patients suspected to COVID-19 referred and admitted to Imam Hussein Hospital in Tehran, Iran between February 20, 2020 and April 19, 2020 that assessed by CT scanning were prospectively assessed. All CT scans were interpreted by two independent high-experienced radiologists with high diagnostic agreement. Results: In total, 5211 individuals suspected to COVID-19 were assessed by CT scanning in our center. Of those, the diagnosis of the disease was definitively confirmed in 1357 cases with the prevalence rate of 26.0%. Among the confirmed cases of the disease with CT positivity, 32 had single pulmonary nodules and therefore, the prevalence rate of single nodules to all initial suspected cases was revealed to be 0.6% and to all subjects with definitive diagnosis of disease with positive CTs to be 2.4%. The characteristics of nodules (size, type, or location) were independent to patients' age and gender. Conclusion: The appearance of pulmonary single nodules may be predictive for early diagnosis and confirming COVID-19 disease in suspected cases.