COVID-19 is a new type of outbreak that may have a profound impact on public health. According to the new coronavirus-infected pneumonia diagnosis and treatment plan (trial version 6) issued by the National Health Commission of the People’s Republic of China, the group included patients in the study in terms of epidemiological history, clinical manifestations (including imaging manifestations), and pathogenic examination. The cases were identified as new coronaviruses, and all were confirmed cases in Heilongjiang Province. At present, the typical imaging features of COVID-19 are one of the important clinical manifestations in the "diagnostic criteria for suspected cases". It can be seen that the results of imaging studies are very important for the classification of cases and the choice of further treatment options. In addition, the plain CT scan of the chest has a clear manifestation of inflammatory changes in the lungs at various stages, and is the preferred imaging method for COVID-19 screening and diagnosis. The ground-glass opacity (100%) was observed in all 10 patients included in the study. It can be seen that ground-glass opacity is the most characteristic imaging feature of COVID-19. Moreover, the disease is likely to cause bilateral lung lobe involvement (8/10, 80%). Nine patients (90%) had ≥ two lung lobe, of which 6 (60%) were involved in extralobular lobe involvement, the upper lobe of the right lung is a common site of the disease (8/10, 80%). Thickening of lobular septum and fibrous cords are also multiple imaging features of the disease (6/10, 60%; 6/10, 60%, respectively). Other imaging findings include pulmonary nodules (2/10, 20%), emphysema (1/10, 10%), calcifications (3/10, 30%), and mediastinal lymphadenopathy (1/1 10, accounting for 10%). Pleural effusion is a negative feature associated with this disease.
One patient in this group underwent follow-up CT examinations: the initial CT findings were mainly ground-glass opacity, involving both lungs, and more often the disease course was in the advanced stage. After treatment, a comparison of the CT examination and the previous film showed that although the ground-glass opacities of the lungs were absorbed more than before, the ground-glass opacities at the bottom of the lungs had changed, and the ground-glass opacities and consolidation coexisted. It is still considered that the course of disease is in progress Period-based. The comparison of the CT results of the third review of the patient compared with the previous film showed that the ground-glass opacity and consolidation of the lungs were absorbed earlier, the density was reduced, and the lobular interval was further thickened with multiple fibrous cords, it is a "paving stone" sign, considering that the exudate is absorbed or mechanized by the body. Generally, the lobular space is thickened with fibrous cords, and the disease course is mostly considered to be dissipating. This is also consistent with the recently published imaging features of the course of the COVID-19 course .
Viruses are a common cause of respiratory infections. The imaging findings of viral pneumonia are similar to other infectious and inflammatory lung diseases. Viruses in the same virus family have similar pathogenesis. Therefore, CT may help to identify the imaging features of patients with immune function . Some data indicate that the CT findings of COVID-19 have many similar characteristics to other types of coronavirus (SARS) . The SARS outbreak was also caused by a coronavirus. Therefore, the diagnostic experience of these epidemics may help manage the current epidemic. It may be valuable to correlate imaging findings from SARS patients with imaging findings from COVID-19 patients. In terms of CT manifestations, the two diseases are similar, such as ground-glass opacity and consolidation. Some research results show that the most common CT imaging manifestation of SARS is the presence of ground-glass opacity . Müller et al.  reviewed the imaging findings of 12 SARS patients and found that unilateral / bilateral ground-glass opacity was the most common imaging manifestation of patients. Lee et al.  reviewed the radiological characteristics of 138 SARS patients and found that the lesions were mainly distributed in the peripheral zone of the two lungs, and there was no associated pleural effusion or hilar lymphadenopathy, which is consistent with the findings of this study. Pulmonary lesions often involve the extrapulmonary bands, and the cause of the subpleural area may be related to the pathogenesis of viral pneumonia in the early stage involving the terminal bronchi and respiratory bronchioles, and then the entire lobules and diffuse alveoli . Similarly, SARS manifestations of thickened lobular septum and "paving stone sign" have also been found in some of our patients . In our study, the multifocal nature of COVID-19 was more common than SARS in 2003 .
There is one special sample in this study. The 25-year-old young patient had no clinical symptoms at the time of initial diagnosis, but the CT examination revealed a round ground-glass opacity in the right upper lobe. The further positive of the new coronavirus nucleic acid test virus is to show the sensitivity of CT examination and the importance of clinical treatment options. The results of negative clinical symptoms in patients with known infections indicate that COVID-19 cannot be completely ruled out by the patient alone, especially in the early stages of infection.
The vast majority of patients in this study (80%) had varying degrees of fever, and half of the patients had respiratory symptoms (50%). Many patients in this group also have non-respiratory symptoms, including headache, nausea, and fatigue (70% in total), so clinicians need to pay great attention to such non-respiratory symptoms. In laboratory tests, most patients had elevated C-reactive protein (70%) and serum amyloid A (80%); a few patients (30%) had elevated D-dimers.
Our study has several limitations: (1) we have a relatively small number of patients; (2) we do not have chest X-rays, and the study is limited to chest CT because CT is more sensitive to early and / or mild disease and is more sensitive than previous SARS The outbreak is similar to . However, it is undeniable that chest X-ray examination may have some practicality, especially in medical environments with high incidence of disease but limited resources, which has the potential to serve as a first-line screening tool.