基于双气相配准定量CT在无症状吸烟者肺小气道病变中的应用

Application of Quantitative CT Based on Dual Gas Phase Registration in Asymptomatic Smokers with Pulmonary Small Airway Lesions

目的采用CT双气相配准技术对无症状吸烟者的肺小气道病变进行定量分析,并探讨其与肺功能的相关性。资料与方法前瞻性收集延安大学附属医院2019年9月—2020年10月正常健康体检不吸烟者34例、低吸烟指数者28例和高吸烟指数者33例,行呼、吸双相CT扫描,将原始数据导入数字肺定量分析软件进行配准并小气道分析,得出CT定量指标:正常肺组织(Normal%)、小气道病变(fSAD%)、肺气肿(Emph%)、吸气相小于-950 Hu体素百分比(IN-950%)、吸气相平均肺密度(MLD-IN)、呼气相小于-856 Hu体素百分比(EX-856%)、呼气相平均肺密度(MLD-EX)。3组间CT定量指标和肺功能指标呼气峰流速(PEF)、1 s末用力呼气容积实测值占预计值百分比(FEV1%)、FEV1占用力肺活量的百分比(FEV1/FVC)的差异采用单因素方差分析或非参数检验,并分析CT定量指标与肺功能的相关性。结果3组间CT定量指标IN-950%、MLDIN差异无统计学意义(Z=2.106、1.367,P>0.05),Normal%(F=46.506,P=0.000)、fSAD%(F=57.126,P=0.000)、Emph%(Z=53.140,P=0.000)、MLD-EX(Z=14.902,P=0.000)、EX-856%(Z=15.902,P=0.000)比较,差异有统计学意义。3组间肺功能指标PEF(F=14.376,P=0.001)、FEV1%(Z=7.559,P=0.023)、FEV1/FVC(Z=25.856,P=0.000)差异有统计学意义。3组fSAD%指标吸烟指数由低到高分别为10.39%、13.67%、25.71%,Emph%指标分别为3.65%、4.67%、10.55%。随着吸烟指数增加,Normal%、MLD-EX、PEF、FEV1%、FEV1/FVC逐渐下降,fSAD%、Emph%、EX-856%逐渐上升。吸烟者CT定量指标Normal%、fSAD%、Emph%、MLD-EX、EX-856%与肺功能PEF和FEV1/FVC均有相关性(P<0.05)。fSAD%与肺功能指标FEV1/FVC的相关性最高(r=-0.576,P=0.000),其次是Emph%(r=-0.565,P=0.000)。结论基于双气相配准定量CT能测量无症状吸烟者的肺内小气道病变,fSAD%、Emph%能更敏感地发现无症状吸烟者的肺功能改变。

Purpose To quantitatively analyze the small airway lesions of asymptomatic smokers via CT dual-gas registration technique,and to explore its correlation with lung function.Materials and Methods A total of 34 non-smokers,28 smokers with low smoking index and 33 smokers with high smoking index in the Affiliated Hospital of Yan'an University from September 2019 to October 2020 were collected prospectively.All participants were scanned by dual-phase CT with respiration and inhalation,respectively,and all original data were further imported into digital lung quantitative analysis software for registration and small airway analysis.The quantitative indexes of CT were obtained as follows:normal lung tissue area percentage(Normal%),small airway lesion area percentage(fSAD%),emphysema area percentage(Emph%),inspiratory phase less than-950 Hu pixel percentage(IN-950%),inspiratory phase average lung density(MLD-IN),Expiratory phase less than-856 Hu voxel percentage(EX-856%),expiratory phase mean lung density(MLD-EX).The pulmonary function indexes include peak expiratory flow velocity(PEF),the percentage of measured expiratory volume at the end of 1 s to predicted value(FEV1%)and the percentage of FEV1 to forced vital capacity(FEV1/FVC).The differences of CT quantitative indicators and lung function among the three groups were analyzed by one-way ANOVA or nonparametric test,the correlation between CT quantitative indicators and lung function was analyzed.Results There were no significant differences in CT quantitative indicators IN-950%and MLD-IN among these three groups(Z=2.106 and 1.367,P>0.05).There were statistically significant differences in the Normal%(F=46.506,P=0.000),FSAD%(F=57.126,P=0.000),Emph%(Z=53.140,P=0.000),MLD-EX(Z=14.902,P=0.000)and EX-856%(Z=15.902,P=0.000)among these three groups,respectively.There were statistically significant differences in pulmonary function indexes PEF(F=14.376,P=0.001),FEV1%(Z=7.559,P=0.023)and FEV1/FVC(Z=25.856,P=0.000)among these three groups.The fSAD%index of the three groups was 10.39%,13.67%and 25.71%from low to high smoking index,and the Emph%index was 3.65%,4.67%and 10.55%,respectively.With the increase of smoking index,Normal%,MLD-EX,PEF,FEV1%and FEV1/FVC decreased gradually,while fSAD%,Emph%and EX-856%increased gradually.The CT quantitative indicators of smokers,including the Normal%,fSAD%,Emph%,MLD-EX,EX-856%,were significantly correlated with lung function PEF and FEV1/FVC(all P<0.05).The correlation between fSAD%and lung function FEV1/FVC was the highest(r=-0.576,P=0.000),followed by Emph%(r=-0.565,P=0.000).Conclusion Quantitative CT based on two-phase registration can measure the small airway lesions in the lungs of asymptomatic smokers,and fSAD%and Emph%can more sensitively find the changes of lung function of asymptomatic smokers.