新型冠状病毒奥密克戎变异株胸部CT征象演变及与野生型对照研究

Evolution of chest CT features of Omicron variant of COVID-19 and comparison with wild-type

目的通过分析和比较奥密克戎(Omicron)变异株和野生型(WT)变异株感染病人的CT征象及临床资料,总结Omicron病人胸部病变演变规律。方法回顾性收集天津地区新型冠状病毒感染(COVID-19)病人的住院临床及影像资料,纳入2022年Omicron感染病人416例和2020年WT感染病人128例,2组分别有134、123例病人住院期间胸部CT发现肺炎。采用χ2检验、Fisher确切概率检验、Mann-Whitney U检验比较2组间临床表现、疫苗接种率、CT阳性率、CT视觉严重程度评分(VSS)及间隔时间。分析Omicron组134例病人出现肺炎的CT征象随时间动态变化规律。结果与WT组相比,Omicron组病人较年轻,咽痛和鼻塞症状者更多(均P<0.05)。Omicron组疫苗接种率为89.66%,WT组均未接种疫苗。Omicron组病人入院首次和住院期间的胸部CT阳性率分别为14.42%和32.21%,均低于WT组病人(92.97%和96.09%)(均P<0.05)。Omicron组首次阳性CT和高峰CT VSS评分均低于WT组,高峰CT的间隔时间[10(9,13)d]长于WT组[9(6,13)d](均P<0.05)。Omicron组以胸膜下区磨玻璃密度为CT主要表现(急性期),肺实变随时间进展增多。发病10 d后小叶内间隔增厚、纤维索条、胸膜下线、牵拉性支气管扩张等征象增多(机化期)。结论Omicron病人肺炎发生率低、范围小,高峰时间出现晚。部分CT机化征象有助于临床医生区分Omicron病程急性期和机化期,从而调整相应治疗方案。

Objective By analyzing and comparing the CT signs and clinical data of patients infected with the Omicron mutant strain and the wild-type(WT)strain,the evolution of chest lesions in Omicron patients was summarized.Methods The clinical and imaging data of hospitalized patients with coronavirus disease 2019(COVID-19)in Tianjin were collected retrospectively,including 416 patients with Omicron infected in 2022 and 128 patients with WT infected in 2020.There were 134 and 123 patients presented COVID-19-related pneumonia lesion on chest CT in the Omicron and WT groups respectively.Chi-square test,Fisher’s exact test,and Mann-Whitney U test were used to compare the clinical symptoms,vaccination rate,and positive rate,visual severity score(VSS)and interval time of CT between the two groups.The dynamic evolution of CT features of 134 patients with pneumonia of the Omicron group were analyzed.Results Compared with the WT group,the Omicron patients were significant younger and presented more pharyngalgia and stuffy running noses(all P<0.05).The vaccination rate was 89.66%in the Omicron group,and none in the WT group.The positive rates were 14.42%and 32.21%on the first CT at admission and follow-up CT during hospitalization in the Omicron group,which were significantly lower than that in the WT group(92.97%,96.09%,all P<0.05).The VSSs at admission and time with the most severe symptoms in the Omicron group were both significantly lower than that in the WT group(P<0.05).The time interval between the two CT exams was significantly longer in the Omicron group[median time,10 days(IQR:9-13 days)]than in the WT group[median time,9 days(IQR:6-13 days)](P<0.05).In the Omicron group,ground glass opacity(GGO)in the subpleural area was the main CT manifestation(acute phase),and consolidation increased with time.The features such as intralobular septal thickening,fibrous cord,subpleural line,and tractive bronchiectas is increased after 10 days of onset(mechanized phase).Conclusion Omicron patients have a low incidence and small extent of pneumonia and late peak time.Some of the organizing signs on CT are helpful to determine the phases of the Omicron-related pneumonia,and thus clinicians could adjust the treatment plan accordingly.