Manual severity evaluation methods for novel coronavirus pneumonia based on computed tomography imaging

Computed tomography (CT) examination plays an indispensable role in the diagnosis of coronavirus disease-2019 (COVID-19). Many studies have evaluated the severity of COVID-19 based on CT images, with the severity of COVID-19 being evaluated either manually or by using artificial intelligence. In this review, the recently reported methods for manually evaluating COVID-19 severity based on CT images are summarized and divided into three categories: evaluation based on the extent of abnormalities;evaluation based on the characteristics of abnormalities;and evaluation based on both the extent and characteristics of abnormalities.