Computed tomography chest in COVID-19: When & why?

Computed tomography (CT) of the chest plays an important role in the diagnosis and management of coronavirus disease 2019 (COVID-19), but it should not be used indiscriminately. This review provides indications of CT chest in COVID-19 suspect, positive and recovered patients based on the current scientific evidence and our personal experience. CT chest is not indicated as a routine screening modality due to its poor sensitivity and specificity. However, it is useful in a small subset of COVID-19 suspects who test negative on reverse transcription-polymerase chain reaction (RT-PCR) with normal/indeterminate chest X-ray (CXR) but have moderate-to-severe respiratory symptoms and high index of clinical suspicion. CT chest is not indicated in every RT-PCR–positive patient and should be done only in specific clinical scenarios, where it is expected to significantly contribute in the clinical management such as COVID-19 patients showing unexplained clinical deterioration and/or where other concurrent lung pathology or pulmonary thromboembolism needs exclusion. Serial CXR and point-of-care ultrasound are usually sufficient to evaluate the progression of COVID-19 pneumonia. CT chest is also indicated in COVID-19–positive patients with associated co-morbidities (age >65 yr, diabetes, hypertension, obesity, cardiovascular disease, chronic respiratory disease, immune-compromise, etc.) who, despite having mild symptoms and normal/indeterminate CXR, record oxygen saturation of <93 per cent at rest while breathing room air or de-saturate on six-minute walk test. Finally, CT chest plays a crucial role to rule out lung fibrosis in patients recovered from COVID-19 infection who present with hypoxia/impaired lung function on follow up. In conclusion, though CT chest is an indispensable diagnostic tool in COVID-19, it should be used judiciously and only when specifically indicated.