The Diagnostic Value of CT scans in the Process of Diagnosing COVID 19 in medical Centers

Introduction: Coronavirus disease (COVID 19) has spread around the world since the beginning of 2020. The definitive diagnosis of COVID19 is RT-PCR laboratory test. However because of low sensitivity, the use of the chest CT scan has become important for the rapid diagnosis and clinical decision-making. This study aims to define the diagnostic value of CT scans in the process of diagnosing COVID 19 in medical Centers. Methods: This study is a rapid health technology assessment (HTA) and had two major phases. In Phase 1, Rapid review was done for defining sensitivity and specificity rate of CT. During this phase, studies related to the diagnostic and technical data on the use of CT in the diagnosis of COVID19 was reviewed and sensitivity and specificity of CT in these studies were extracted. In phase 2, sequential testing was run to evaluate the diagnostic value of chest CT to diagnose COVID 19 according to 2 scenarios before and after adding RT-PCR test result. Results: CT scan has a high sensitivity to diagnosing cases of COVID 19. Due to its low specificity, relying on CT scan to diagnose COVID 19 alone in medical centers, can lead to a significant proportion of false positive cases. This Study showed if the probability of COVID 19 before the CT scan were about 50%, with a positive CT scan, this probability will be between 60 and 70% depending on the CT specificity. Conclusion: With the available evidence, the use of CT scan lonely is not sufficient for diagnosis. The RT-PCR test is also necessary to improve the diagnosis and continue the process of treatment and isolation of patients.