Patterson R P, Zhang J, Mason L I, Jerosch-Herold M
Department of Biomedical Engineering, University of Minnesota, Minneapolis 55455, USA.
Physiol Meas. 2001 Feb;22(1):159-66. doi: 10.1088/0967-3334/22/1/319.
A study was conducted using the Sheffield electrical impedance tomography (EIT) portable system DAS-01 P to determine the change in the cardiac image with electrode position, lung volume and body position. Sixteen electrodes were positioned in three transverse planes around the thorax at the level of the second intercostal space, at the level of the xiphisternal joint, and midway between upper and lower locations. Data were collected at each electrode level with the breath held at end expiration and after inspiring 0.5, 1 and 1.5 l of air with the subject in both the supine and sitting position. These data were analysed using a Matlab developed program that calculates the average resistivity change in the cardiac region from automatically determined borders. Results show significant individual variability with electrode position and air volume. The middle electrode most consistently shows an increase in impedance in the region of the heart during systole. In some subjects the change in the ventricular-volume-like curve showed a greater than 50% change as a function of lung volume. The pattern of variability with electrode position was not consistent among subjects. In one subject MRI images were obtained to compare actual structures with those seen in the EIT image. The results suggest that using these electrode locations reliable and consistent data, which could be used in clinical applications, cannot be obtained.
使用谢菲尔德电阻抗断层扫描（EIT）便携式系统DAS - 01 P进行了一项研究，以确定心脏图像随电极位置、肺容量和身体位置的变化。16个电极位于胸廓周围的三个横断面上，分别在第二肋间水平、剑突关节水平以及上下位置的中间位置。在每个电极水平收集数据，受试者在呼气末屏气时以及在仰卧位和坐位吸入0.5、1和1.5升空气后进行收集。使用一个由Matlab开发的程序对这些数据进行分析，该程序根据自动确定的边界计算心脏区域的平均电阻率变化。结果显示，电极位置和空气量存在显著的个体差异。中间电极在收缩期最一致地显示心脏区域的阻抗增加。在一些受试者中，心室容积样曲线的变化显示出作为肺容量函数的超过50%的变化。电极位置的变化模式在受试者之间并不一致。对一名受试者获取了MRI图像，以将实际结构与EIT图像中看到的结构进行比较。结果表明，使用这些电极位置无法获得可用于临床应用的可靠且一致的数据。
