Pulletz Sven, van Genderingen Huibert R, Schmitz Gunnar, Zick Günther, Schädler Dirk, Scholz Jens, Weiler Norbert, Frerichs Inez
Department of Anaesthesiology and Intensive Care Medicine, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
Physiol Meas. 2006 May;27(5):S115-27. doi: 10.1088/0967-3334/27/5/S10. Epub 2006 Apr 20.
The measurement of regional lung ventilation by electrical impedance tomography (EIT) has been evaluated in many experimental studies. However, EIT is not routinely used in a clinical setting, which is attributable to the fact that a convenient concept for how to quantify the EIT data is missing. The definition of region of interest (ROI) is an essential point in the data analysis. To date, there are only limited data available on the different approaches to ROI definition to evaluate regional lung ventilation by EIT. For this survey we examined ten patients (mean age +/- SD: 60 +/- 10 years) under controlled ventilation. Regional tidal volumes were quantified as pixel values of inspiratory-to-expiratory impedance differences and four types of ROIs were subsequently applied. The definition of ROI contours was based on the calculation of the pixel values of (1) standard deviation from each pixel set of impedance data and (2) the regression coefficient from linear regression equations between the individual local (pixel) and average (whole scan) impedance signals. Additionally, arbitrary ROIs (four quadrants and four anteroposterior segments of equal height) were used. Our results indicate that both approaches to ROI definition using statistical parameters are suitable when impedance signals with high sensitivity to ventilation-related phenomena are to be analyzed. The definition of the ROI contour as 20-35% of the maximum standard deviation or regression coefficient is recommended. Simple segmental ROIs are less convenient because of the low ventilation-related signal component in the dorsal region.
通过电阻抗断层扫描（EIT）测量局部肺通气已在许多实验研究中得到评估。然而，EIT在临床环境中并未常规使用，这是因为缺少一个关于如何量化EIT数据的便捷概念。感兴趣区域（ROI）的定义是数据分析中的一个关键点。迄今为止，关于通过EIT评估局部肺通气的不同ROI定义方法的可用数据有限。在本次研究中，我们检查了10例在控制通气下的患者（平均年龄±标准差：60±10岁）。局部潮气量被量化为吸气至呼气阻抗差异的像素值，随后应用了四种类型的ROI。ROI轮廓的定义基于以下计算：（1）阻抗数据每个像素集的标准差的像素值，以及（2）各个局部（像素）与平均（全扫描）阻抗信号之间线性回归方程的回归系数。此外，还使用了任意ROI（四个象限和四个等高度的前后节段）。我们的结果表明，当要分析对通气相关现象具有高灵敏度的阻抗信号时，使用统计参数的两种ROI定义方法都是合适的。建议将ROI轮廓定义为最大标准差或回归系数的20%至35%。简单的节段性ROI不太方便，因为背部区域与通气相关的信号成分较低。
