Introduction
Since December 2019, a number of cases of pneumonia with fever, cough, and dyspnea as clinical manifestations have been found in Wuhan, Hubei Province, China [1]. The analysis of the whole genome sequence of the respiratory samples suggests that it is a new type of betacoronavirus [2], which resembled severe acute respiratory syndrome coronavirus (SARS-CoV) [3]. On February 11, 2020, the World Health Organization (WHO) officially named it coronavirus disease (COVID-19).
WHO has recently declared the outbreak a public health emergency of international concern [4]. As of March 12, 2020, 124,922 laboratory-confirmed and clinical-confirmed cases have been documented globally (i.e., the USA, Vietnam, Germany) [4–7], 80,980 laboratory-confirmed and clinical-confirmed cases and 3173 deaths in China as of March 12, 2020 [8]. On Jan. 15, 2020, the first confirmed family cluster was reported in Zhuhai, China, where the parents presented with unexplained pneumonia after coming from Wuhan to visit their daughter who was living in Zhuhai, China; afterwards, the daughter also developed respiratory symptoms and infection with SARS-CoV-2 was confirmed.
As of February 13, the journal Radiology has published several articles on the imaging features of COVID-19 [9–12], but all of them are descriptive analyses. In February 2020, the Chinese Society of Radiology issued the radiologic diagnosis of pneumonia with COVID-19. CT plays an important role in the screening and diagnosis of COVID-19. The first edition of the experts [13] divided CT manifestations into three stages: early, progressive, and severe according to the extent and features of the pulmonary abnormalities. However, it did not clarify the relationship between the extent of inflammation and the clinical presentation of the patient. In this study, we used a simple convenient method to quantify the imaging findings.