Key Points of Clinical and CT Imaging Features of 2019 Novel Coronavirus (2019-nCoV) Imported Pneumonia Based On 21 Cases Analysis

wenxiu Wu; zhifeng xu; yabin Jin; aizhen Pan

The copyright holder for this preprint (which was not peer-reviewed) is . https://doi.org/10.1101/2020.03.03.20030775 doi: medRxiv preprint bilateral lungs, and all cases showed significant peripheral distribution characteristics, wich was consistent with previous studies [14] [15] [16] .We speculated that the main reasons for the distribution characteristics of NCP as followed: 1)The 2019-nCov infect alveolar epithelial cells through angiotensin-converting enzyme 2 (ACE2) and cause acute lung injury [17] .The peripheral lobe of the lung is relatively well developed, abundant alveolar epithelial cells may express more ACE2. 2) The ventilation function of alveolar tissue in the peripheral part of the lung is relatively weak, which may more easily lead to the aggregation of high concentration of virus particles and the onset of disease. In addition, some scholars believe that virus particles are extremely small (2019-nCov is about 120nm), which can directly enter the distal alveoli with respiration. In this study, CT features of NCP patients mainly displayed GGO (100%), vascular enlargement sign (76.5%) and cobblestone/reticular pattern (70.6%), as followed by consolidation and mixed pattern (GGO and consolidation) with about 52.9%. While mediastinal lymph nodes and pleural effusion were rare, which was basically consistent with literature reports [14, 15] .In general, the lung characteristics of NCP patients were mainly associated with pulmonary interstitial inflammation, which was similar to Middle East respiratory syndrome(MERS) [18] and Severe Acute Respiratory Syndrome(SARS) [19] caused by coronavirus. In fact, the pathological characteristics of NCP were confirmed to be similar to SARS and MERS [20] Previous reports revealed that GGO as the key CT feature.It can exists for a long time throughout the course of the disease, and may be unique CT feature in some early patients [15, 16] . In the recent study, GGO feature was observed in all NCP patients. Pathological basis of GGO is mainly diffuse alveolar injury, accompanied by cell fibromyxoid exudate,and lung transparent membrane formation. GGO at the early stage could be completely absorbed and improved after effective treatment [21] . With the development of the disease, the interlobular septa thickened on the basis of GGO, and showed typical cobblestone/reticular pattern,and when increased exudation in the alveoli and alveolar collapse resulted in consolidation. Compared with the mild group patients, the incidence of consolidation, mixed pattern, air-bronchogram, dilated bronchi with thickened wall and fibrosis significantly increased in severe patients. In addition, cobblestone/reticular pattern and vascular enlargement sign were both common findings in severe patients without significant different. It is suggested that the changes of pulmonary imaging characteristics can effectively reflect the changes of lung tissue and functional injury.Vascular enlargement in or around the lesions were considered to be an important features for NCP diagnosis,76.5% patients in our study presented this features. This may be due to inflammatory vascular congestion, or to thickening or fluid buildup in the perivascular interstitium [20] . Additionally,all these findings suggest the presence of fibrosis, which also presented commonly in patients underwent SARS and MERS.In this study, consolidation and mixed manifestations were observed in 52.9% of NCP patients, and the incidence rate was up to 100%