Wang Y, Schimpf P H, Haynor D R, Kim Y
Department of Bioengineering, University of Washington, Seattle 98195, USA.
IEEE Trans Biomed Eng. 1998 Jul;45(7):877-84. doi: 10.1109/10.686795.
We studied via computer simulation the effects of electrode diameter, electrode length, interelectrode spacing, and tissue size on the accuracy of measured tissue resistivities and anisotropy ratios obtained with the widely used four-electrode technique. Such measurements commonly assume an ideal situation in which the four electrodes are infinitesimally small and the tissue is semi-infinite. Our study shows that these geometric factors can significantly affect measured resistivities, particularly for anisotropic tissues. The measured anisotropy ratio is decreased by either 1) increasing the electrode diameter or length relative to the interelectrode spacing of the probe or 2) decreasing tissue size. We have provided an equation for estimating errors in the measured anisotropy ratio from the parameters of electrode and tissue geometries. The simulation findings are supported by our in vitro experimental results.
我们通过计算机模拟研究了电极直径、电极长度、电极间距和组织大小对使用广泛的四电极技术获得的测量组织电阻率和各向异性比率准确性的影响。此类测量通常假定一种理想情况，即四个电极无限小且组织为半无限大。我们的研究表明，这些几何因素会显著影响测量的电阻率，尤其是对于各向异性组织。测量的各向异性比率会因以下两种情况之一而降低：1）相对于探头的电极间距增加电极直径或长度；2）减小组织大小。我们提供了一个方程，用于根据电极和组织几何参数估计测量各向异性比率中的误差。模拟结果得到了我们体外实验结果的支持。
