Typical radiological progression and clinical features of patients with coronavirus disease 2019.

We aimed to describe typical radiological features and progression of Coronavirus disease 2019 (COVID-19) patients. We reviewed the chest CT scans, laboratory findings, and clinical records of 66 COVID-19 patients who were admitted to affiliated hospitals of Nanchang university, Nanchang, China, from Jan 21 to Feb 2, 2020. CT was used to evaluate the radiological characteristics of COVID-19 patients. Only 4 patients (4/66, 6%) claimed their exposure to COVID-19 pneumonia patients. The major symptoms were fever (60/66, 91%) and cough (37/66, 56%). The predominant features of lesion were scattered (43/66, 65%), bilateral (50/66, 76%), ground-glass opacity (64/66, 97%), and air bronchogram sign (47/66, 71%). Forty-eight patients (48/66, 73%) had more than two lobes involved. Right lower lobe (58/66, 88%) and left lower lobe (49/66, 74%) were most likely invaded. Twelve patients (12/66, 18%) had at least one comorbid condition. Pleural traction (29/66, 44%), crazy paving (15/66, 23%), interlobular septal thickening (11/66, 17%), and consolidation (7/66, 11%) were also observed. The typical radiology features of COVID-19 patients are scattered ground-glass opacity in the bilateral lobes. Fever and cough are the major symptoms. Evaluating chest CT, clinical symptoms, and laboratory results could facilitate the early diagnosis of COVID-19, and judge disease progression.


INTRODUCTION
Since December 2019, a series of unknown pneumonia caused by a novel coronavirus broke out in Wuhan, Hubei, China. This new coronavirus was named as severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) or 2019 novel coronavirus (2019-nCoV) [1]. The disease caused by 2019-nCoV is coronavirus disease 2019 (COVID-19), which had been confirmed to be a global pandemic by the World health organization (WHO). By April 8 2020, more than 1, 350, 000 infected cases and 79, 000 deaths have been caused by COVID-19 [2]. COVID-19 has been effectively prevented and controlled in China, Singapore, South Korea, and Japan right now, but 2019-nCoV is spreading fast in Europe and the United State.
Obviously, the threat to the global health and economy by 2019-nCoV will last for a long time [3,4].

RESULTS
Total 66 COVID-19 pneumonia patients were admitted to three affiliated hospitals of Nanchang university between Jan 21 to Feb 2, 2020 ( In this study, we presented some common and typical radiology changes (Figures 1 and 2). The most common radiology characteristic seen on the CT was ground-glass opacity (64/66, 97%). Most ground-glass opacities were characterized by scattered and bilateral lesions ( Figure 1A and 1B). The CT scans of 15 (15/66, 23%) patients shown crazy paving ( Figure 1C), and consolidation was observed in 7 (7/66, 11%) patients ( Figure 2A). In addition, air bronchogram sign (47/66, 71%, Figure 1D), pleural traction (29/66, 44%), interlobular septal thickening (11/66, 17%), and halo sign (3/66, 5%, Figure 2B) were also observed ( Table 2). Bronchiectasia was observed in the right lower lobe of one patient with bilateral ground-glass opacity ( Figure 2C).    Figure 1B). Patient 2, 47-year-old man with type 2 diabetes, whose CT scan presented rapid radiology progression ( Figure 3A, 3B). The radiological change of COVID-19 pneumonia develops fast during the first seven days ( Figure 3C, 3D). Some of patch lesion could be absorbed and change into reticular spline lesion ( Figure 4A, 4B). Meanwhile, some patients achieved rapid recovery with significant improvement of CT sign ( Figure 4C, 4D) and clinical symptoms. We also did some CT follow-up scans for few patients, which showed the aggravated progression of disease since admission and rapid recovery after treatment ( Figures 5 and 6). Disappearance of lesions and significant improvement of clinical symptoms were observed in two patients ( Figure 5: a 54-year-old male patient; Figure 6: a 54-year-old female patient).

DISCUSSION
2019-nCoV, an enveloped positive-sense RNA virus, is the seventh member of the coronaviridae family [10]. It is estimated that 2019-nCoV could cause 1%-6% mortality rate depending on different regions, which is lower than MERS-CoV (10%) and SARS-CoV (37%)  AGING [5,11], but the high infectivity of the pathogen has caused a global pandemic. 2019-nCoV has became a huge threat for the global health, economic development, and social stability.

AGING
Previous study indicated that old age population with comorbidities were susceptible to infection of 2019-nCoV [12]. In our cohort, there were 45 (45/66, 68%) patients under 50 years-old, and only 12 (12/66, 8%) patients had at least one comorbid condition. Small cohorts and differences in demographic characteristics might account for this discrepancy. Previous study suggested that 73% (30/41) patients were male [1], which is inconsistent with another study [13]. In our study, male infected patients account for 65% (43/66). The difference of gender distribution might also due to small cohorts. By Mar 23, 2020, two patients (78 and 47 years old, respectively) in this study had died, and both had comorbid conditions.
It is worth mentioning that 41 patients (41/66, 62%) patients had no obvious exposure history indicating that they might be infected by latent infection patients.
Latent infection should attract the attention of people, because the clinical appearance of latent infection patients is not consistent with real disease progression. Meanwhile, the latent infection patients indeed have infectivity. When participating in group activities or gathering, wearing mask should be an effective method to prevent infectivity by asymptomatic patients. Some countries such as India and Indonesia have a large population and the medical condition of them is not optimistic. For the people who lack sufficient medical protection, it is effective to prevent and control virus spreading by avoiding gathering, wearing mask in the crowd, regular ventilation at home.
Fever and cough were the most common symptoms in the COVID-19 patients. Self-isolation and wearing mask are still effective and economic method for fever people who have mild symptoms, but if symptoms aggravate, professional and medical measures should be taken because of the high mortality rate.
Due to special structure, right lower lobe and left lower lobe were most commonly involved, which is in line  AGING with previous study [13]. Most COVID-19 patients presented bilateral lungs lesion with scattered distribution. However, unilateral lesion is more common in the early infection stage of MERS-CoV and SARS-CoV [14,15]. The most common image feature was ground-glass opacity, which was found in 64 (64/66, 97%) patients. Other features such as crazy paving, consolidation, air bronchogram sign, and pleural traction were also observed. However, these radiological characteristics could be found in other viral pneumonia caused by MERS-CoV, SARS-CoV, and adenovirus.
RT-PCR has been viewed as the gold standard for COVID-19 pneumonia diagnosis. While, many countries are facing the shortage of nucleic acid test reagent. Meanwhile, the it nucleic acid test costs at least 4-5 hours including throat swab collection, RNA extraction, and RT-PCR. Chest CT could provide effective and fast evidence for the clinical diagnosis of COVID-19 pneumonia. Imaging findings could also indicate the prognosis. The radiological features of some patients might worsen fast indicating a poor prognosis ( Figure 3A, 3B).
Our study had some limitations. Due to short time for data collection, we did not conduct long-term follow-up CT, which is necessary to evaluate the prognosis of patients. In addition, we did not systematically investigate the radiology progression of patients, which could help to judge disease course of COVID-19 pneumonia.
In summary, the typical radiology features of COVID-19 pneumonia were characterized by bilateral and scattered ground-glass opacity accompanying with air bronchogram sign, and predominant lesion location in the left lower lobe and right lobe. Sometimes, the clinical symptoms were not consistent with imaging features indicating that asymptomatic patients may account for a certain proportion. Therefore, CT should be an effective, fast, and simple method for the screening, diagnose, and treatment of COVID-19 pneumonia.

Patients
The retrospective study was approved by the ethical committee of affiliated hospitals of Nanchang university. The written informed consent of this research has been waived by the ethics committee of our hospital for the reason that there is no potential risk and this is a retrospective study. The COVID-19 patients identified by RT-PCR or nest-generation sequencing were admitted from Jan 21 to Feb 2, 2020.

CT data acquisition
All patients were examined by CT for 2-6 times at different time points. The patients in the supine position were scanned using Siemens Emotion 16 (Siemens Healthineers, Forchheim, Germany), Phillips iCT 256 (Phillips Healthcare, Andover, MA, USA), or GE revolution frontier (GE Healthcare, Issaquah, WA, USA). Scans were conducted from the apex of lung to the base of lung on the condition that patients were instructed to hold breath during examination. The following scan parameters were used: tube voltage 120 kV, tube current 70-168mAs, pitch 08-1.2 mm, slice thickness 5 mm, matrix 512×512, FOV 55*35cm, axial reconstruction image layer thickness 1-1.5mm. Three experienced radiologists blinded to nucleic acid results of patients, reviewed all CT scans.

Data analysis
Data analysis was performed on SPSS 22.0 (IBM, Armonk, NY, USA). Categorical variables were presented as number (%), and continuous variables were shown as a range.