Department of Radiology, University Medical Centre Utrecht, Heidelberglaan 100, HP E01.132, Postbus 85500, 3508 GA, Utrecht, The Netherlands.
Lung. 2012 Dec;190(6):629-33. doi: 10.1007/s00408-012-9422-8. Epub 2012 Oct 12.
Lung cancer screening CT scans might provide valuable information about air trapping as an early indicator of smoking-related lung disease. We studied which of the currently suggested measures is most suitable for detecting functionally relevant air trapping on low-dose computed tomography (CT) in a population of subjects with early-stage disease.
This study was ethically approved and informed consent was obtained. Three quantitative CT air trapping measures were compared against a functional reference standard in 427 male lung cancer screening participants. This reference standard for air trapping was derived from the residual volume over total lung capacity ratio (RV/TLC) beyond the 95th percentile of predicted. The following CT air trapping measures were compared: expiratory to inspiratory relative volume change of voxels with attenuation values between -860 and -950 Hounsfield Units (RVC(-860 to -950)), expiratory to inspiratory ratio of mean lung density (E/I-ratio(MLD)) and percentage of voxels below -856 HU in expiration (EXP(-856)). Receiver operating characteristic (ROC) analysis was performed and area under the ROC curve compared.
Functionally relevant air trapping was present in 38 (8.9 %) participants. E/I-ratio(MLD) showed the largest area under the curve (0.85, 95 % CI 0.813-0.883), which was significantly larger than RVC(-860 to -950) (0.703, 0.657-0.746; p < 0.001) and EXP(-856) (0.798, 0.757-0.835; p = 0.002). At the optimum for sensitivity and specificity, E/I-ratio(MLD) yielded an accuracy of 81.5 %.
The expiratory to inspiratory ratio of mean lung density (E/I-ratio(MLD)) is most suitable for detecting air trapping on low-dose screening CT and performs significantly better than other suggested quantitative measures.
肺癌筛查 CT 扫描可能提供有价值的信息，作为与吸烟有关的肺部疾病的早期指标的空气滞留。我们研究了目前建议的哪些措施最适合在早期疾病患者的低剂量 CT 上检测到功能相关的空气滞留。
本研究经伦理批准并获得知情同意。在 427 名男性肺癌筛查参与者中，将三种定量 CT 空气滞留测量方法与功能参考标准进行了比较。空气滞留的参考标准来自于残气量与肺总量比（RV/TLC）超过预测值的第 95 百分位数。比较了以下 CT 空气滞留测量方法：衰减值在-860 至-950 亨氏单位之间的体素的呼气至吸气相对体积变化（RVC(-860 至-950)）、呼气至吸气平均肺密度比（E/I-ratio(MLD)）和呼气时低于-856 HU 的体素百分比（EXP(-856)）。进行了接收器操作特征（ROC）分析，并比较了 ROC 曲线下的面积。
38 名（8.9%）参与者存在功能相关的空气滞留。E/I-ratio(MLD)的曲线下面积最大（0.85，95%CI 0.813-0.883），明显大于 RVC(-860 至-950)（0.703，0.657-0.746；p<0.001）和 EXP(-856)（0.798，0.757-0.835；p=0.002）。在灵敏度和特异性的最佳值时，E/I-ratio(MLD)的准确性为 81.5%。
平均肺密度的呼气与吸气比（E/I-ratio(MLD)）最适合在低剂量筛查 CT 上检测空气滞留，其性能明显优于其他建议的定量测量方法。
