This retrospective study was approved by the Institutional Review Board of People’s Hospital of Guangxi Zhuang Autonomous Region, and the requirement for informed consent was waived.
Study Subjects
We performed a retrospective review of 32 consecutive patients with COVID-19 in People's Hospital of Guangxi Zhuang Autonomous Region from January 2020 to March 2020. The diagnosis was established according to the Diagnosis and Treatment Guidelines of COVID-19 in China (trial version fifth) [14], and confirmed by positive real time reverse transcriptase polymerase chain reaction of SARS-CoV-2 in throat swabs or samples from lower respiratory tract. Inclusion criteria required clinical and chest CT data at the beginning of symptoms to evaluate characteristics in the early course of disease. Patients without abnormal manifestations on CT were excluded.
The patients were grouped based on the illness severity defined by the National Health Commission of China. The severe/critical cases met at least one of the following [14] :1) breathing rate ≥ 30 breaths per minute; 2) pulse oximeter oxygen saturation ≤ 93% in a resting state; 3) arteria oxygen tension (PaO2)/inspiratory oxygen fraction (FiO2) ≤ 300 mmHg; 4) respiratory failure (PaO2 < 60 mmHg when breathing ambient air) occurred and mechanical ventilation required; 5) hemodynamic shock; 6) patients with other organ failure needed intensive care unit monitoring and treatment. Five mild patients with normal CT were not included in the study, so the rest cases were place in moderate group.
Data Collection
Data included age, gender, comorbidities (hypertension, diabetes mellitus, heart disease, cerebrovascular diseases, and chronic obstructive pulmonary disease), symptoms, clinical sign, laboratory findings, and CT images were obtained from medical records. Both clinical and radiological parameters at the initial stage were used to gather information on early features that may be related to COVID-19 progression. Time from initial CT examination to severe/critical pneumonia development, and time from symptom onset to severe/critical pneumonia development were calculated.
Ct Scanning Protocol
CT examinations were performed on a 64-detector row SOMATOM go. Top (Siemens Healthineers, Erlangen, Germany), or a 64-detector row Revolution Frontier ES (GE Healthcare, China Branch, Beijing, China), with the following parameters: tube voltage: 120 kVp, tube current with the automatic milliampere technology: 32–250 mAs, pitch: 1.5 or 1, tube rotation time: 0.5 s or 0.75 s, matrix: 512 × 512, slice thickness: 0.6 mm, reconstruction thickness: 1.0 mm. Unenhanced CT scans were obtained for all patients.
Image Viewing And Evaluation
Three chest radiologists with 6, 9 and 11 years of experience who were blinded to the clinical data evaluated the CT findings in consensus. For each of the 32 patients, the initial chest CT images were analyzed for the following points: 1) number of the lesions, indicated as single lesion or multiple lesions; 2) site of the lesions, indicated as right upper lobe (RUL), right middle lobe (RML), right lower lobe (RLL), left upper lobe (LUL), and left lower lobe (LLL); 3) range of lobe involvement: indicated as single lobe involvement, 2 lobes involvement, 3 lobes involvement, 4 lobes involvement, and 5 lobes involvement; 4) transverse distribution of the lesion: described as peripheral, central, and peripheral and central; 5) lesion density, described as ground glass opacity (GGO), consolidation, mixed GGO and consolidation; 6) types of lesion density: classified as 1, 2, and 3; 7) shape of the lesion: described as round, fan-shaped, rectangular, bat-wing, and irregular; 8) other following characteristics: interlobular septal thickening, air bronchogram, microvascular dilation sign, fibrotic streaks, pulmonary emphysema, thickening of pleura, pleural retraction sign, pleural effusion, and lymphadenopathy; 9) extent of lesions: to quantify the extent of lesions and the degree of involvement, a thin section CT score was assigned on the basis of all abnormal areas involved. Each lobe was assigned a score that was based on the following: score 0, denoted no involvement; score 1, < 25% involvement; score 2, 25% to less than 50% involvement; score 3, 50% to less than 75% involvement; and score 4, ≥ 75% involvement. There was a score of 0–4 for each lobe, with a total possible score of 0–20(Figs. 1 and 2).
Statistical Analysis
All statistical analyses were performed with the SPSS 17.0 software package (SPSS Inc., Chicago, IL, United States). Categorical variables were described as frequency rates and percentages, and quantitative variables were described using mean ± SD or median (inter quartile range, IQR) values. The Fisher exact test were used for categorical variables. For quantitative variables, independent sample t test was used for normally distributed data, and Mann-Whitney U test was used for non- normally distributed data. Subsequent univariate and multivariate logistic regression analysis were performed to further identify the initial clinical parameters and baseline CT features associated with the progression of COVID-19 pneumonia. P-values < 0.05 were considered significant.