基于体素的空气潴留定量测量方法的建立及初步临床应用

Establishment and preliminary application of a voxel-based method for the quantitative analysis of air trapping

目的建立并验证基于体素的空气潴留(AT)定量检测方法,并初步探讨其对慢性阻塞性肺疾病(COPD)的诊断价值。方法2015年3月至2016年2月自"数字肺TM"多研究中心连续纳入行深呼、吸气末CT扫描的50名健康志愿者和18例COPD患者。分别采用基于体素定量检测法及常规阈值法测量空气潴留及肺气肿定量参数。所有受试者均在CT检查后3d内行肺功能(PFT)检查。针对健康志愿者,采用配对样本秩和检验方法比较体素法和阈值法所测定量参数值差异,采用Spearman相关性检验比较两种方法定量参数与肺功能的相关性;针对COPD患者,观察肺功能损伤程度近似的患者其空气潴留、肺气肿分布和程度差异性。结果健康志愿者中存在不同程度空气潴留,体素法中位值为5.70%,阈值法中位值为7.96%,差异具有统计学意义(Z=-4.015,P<0.001)。体素法所测定空气潴留百分比、肺气肿百分比参数与肺功能参数一秒末用力呼气容积占预测值百分比(FEV1%)和一秒末用力呼气容积占用力肺活量百分比(FEV1/FVC)的相关性(r值分别为-0.399、-0.494,-0.335和-0.439,P均<0.05),均高于常规阈值法空气潴留与肺气肿参数(r值分别为-0.357、-0.453,-0.284和-0.391,P均<0.05)。体素法还可将肺功能损伤程度近似的COPD患者,进一步分为小气道病变为主、肺气肿为主和混合3种亚型。结论基于体素的空气潴留定量测量方法不仅具有较高敏感度和准确性,且有可能为COPD诊断提供影像学表型,为临床诊疗提供辅助决策。

Objective To establish and validate a voxel-based method for the quantitative detection of air trapping(AT),and to explore its diagnostic value by preliminarily apply this method in chronic obstructive pulmonary disease(COPD)patients.Methods From March 2015 to February 2016,fifty healthy young volunteers and eighteen COPD patients who underwent both end-inspiratory and end-expiratory CT were included from the Digital Lung Multi-center Study.The quantitative parameters of AT and emphysema were measured by both the voxel-based quantitative method and the conventional threshold method,respectively.All subjects underwent pulmonary function examination within 3 days after CT examination.For healthy volunteers,paired sample rank-sum test was used to compare the difference of quantitative parameters between voxel-based method and threshold method,Spearman rank correlation analysis was used to investigate the correlation between quantitative parameters of the two methods and pulmonary function.For COPD patients,the distribution and extent of AT and emphysema in patients with similar degree of pulmonary function(PFT)injury were observed.Results There were varying degrees of AT in the asymptomatic youth,with a median value of 5.70% for the voxel-based method and with a median value of 7.96% for the conventional threshold method,there was significant difference(Z=-4.015,P<0.001).The correlation between AT and emphysema parameters of the voxel-based method and PFT parameters(r=-0.399 and -0.494,-0.335 and -0.439 separately,P<0.05)were higher than that of the conventional threshold method,respectively(r=-0.357 and -0.453,-0.284 and -0.391,respectively;all P<0.05).Furthermore,the voxel-based method can classify COPD patients with similar degree of pulmonary function injury into three subtypes: AT-dominant,emphysema-dominant,and mixed.Conclusions The voxel-based AT quantitative measurement method not only has high sensitivity and accuracy,but also provides imaging phenotype for the diagnosis of COPD and provides assistant decision-making for clinical management.