Tanguay Louis-François, Gagnon Hervé, Guardo Robert
Institut de génie biomédical, Ecole Polytechnique de Montréal, Montréal, QC H3C 3A7, Canada.
IEEE Trans Biomed Eng. 2007 Sep;54(9):1643-9. doi: 10.1109/TBME.2007.892930.
Several papers on induced current electrical impedance tomography (IC-EIT) have dwelt on potential advantages of this technique over conventional EIT which uses applied current (AC-EIT). Experimental evidence that IC-EIT could surpass AC-EIT in similar imaging conditions is lacking. In this paper, we describe a system that can switch rapidly between both AC-EIT and IC-EIT. The system makes it possible to image objects in a saline-filled tank, providing data acquired in identical test conditions for comparing the performance of the two modes. The system uses eight circular coils and 16 electrodes to acquire 120 linearly independent measurements in IC-EIT and 104 in AC-EIT. Difference images were reconstructed from data acquired with both modes using the maximum a posteriori method. Spatial resolution was lower in IC-EIT images than in AC-EIT, especially in the radial direction. IC-EIT also exhibits a bias toward the center for positioning a conductivity perturbation. These results were obtained for a typical coil configuration widely used in the literature and may not be representative of alternate coil configurations. The system described in this paper provides stable experimental conditions for comparing the performance of the two EIT imaging modes and would be a valuable tool for validating new coil configurations.
几篇关于感应电流电阻抗断层成像（IC-EIT）的论文详细阐述了该技术相对于使用外加电流的传统电阻抗断层成像（AC-EIT）的潜在优势。然而，缺乏在相似成像条件下IC-EIT能超越AC-EIT的实验证据。在本文中，我们描述了一种能够在AC-EIT和IC-EIT之间快速切换的系统。该系统能够对充满盐水的水箱中的物体进行成像，提供在相同测试条件下获取的数据，以便比较两种模式的性能。该系统使用八个圆形线圈和16个电极，在IC-EIT中获取120个线性独立测量值，在AC-EIT中获取104个。使用最大后验方法从两种模式获取的数据中重建差异图像。IC-EIT图像的空间分辨率低于AC-EIT，尤其是在径向方向。IC-EIT在定位电导率扰动时也表现出向中心的偏差。这些结果是针对文献中广泛使用的典型线圈配置获得的，可能不代表其他线圈配置。本文描述的系统为比较两种EIT成像模式的性能提供了稳定的实验条件，将是验证新线圈配置的宝贵工具。
