مجله دانشکده پزشکی اصفهان (Aug 2020)
The Role of Computerized Tomography Scan in Diagnosis and Management of Coronavirus Disease 2019 (COVID-19)
Abstract
Coronavirus disease 2019 (COVID-19) is a respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Today we are facing a global epidemic. Fever, cough, fatigue, breathlessness, and smell or taste loss are the most frequent clinical symptoms. In most cases, the symptoms are mild. However, it may occasionally progress to widespread thrombosis, septic shock, or acute respiratory disease syndrome (ARDS). The incubation period is usually about 5 days, but can vary from 2 to 14 days. Early quarantine is vital for preventing the complications and rapid spread of the disease. Real-time reverse transcription-polymerase chain reaction (RT-PCR) of a nasopharyngeal sample is the standard diagnostic test. However, this method is expensive and unavailable in many parts of the country, and has delayed results. On the other hand, computerized tomography scan (CT-scan) is widely available and low-cost throughout the country, and provides immediate results with high sensitivity. Indeed, in some cases, CT-scan is capable of providing evidence for the disease before detection of viral RNA from upper respiratory samples. CT-scan exhibits higher sensitivity, but lower specificity for diagnosis of COVID-19, compared to RT-PCR (sensitivity of 59-78% and 95-98% as well as specificity of approximately 100% and 96% for RT-PCR and chest CT-scan, respectively). Low sensitivity for diagnosis of COVID-19 and ionizing radiation exposure are two major disadvantages of CT-scan, which can be resolved to a large extent by clinical and laboratory correlations and utilizing low-dose CT protocols. It seems that CT-scan can be ordered for diagnosis of COVID-19 when PCR test is not feasible, or in case of high clinical suspicion in spite of negative PCR. In addition, CT-scan plays a major role in assessing the severity, extent and prognosis of the disease in monitoring the response to treatment, and in diagnosis of complications.
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