Bayford R, Hanquan Y, Boone K, Holder D S
Department of Electronic Engineering, Middlesex University, UK.
Physiol Meas. 1995 Aug;16(3 Suppl A):A237-47. doi: 10.1088/0967-3334/16/3a/022.
A novel approach to image reconstruction for electrical impedance tomography (EIT) has been developed. It is based on a constrained optimization technique for the reconstruction of difference resistivity images without finite-element modelling. It solves the inverse problem by optimizing a cost function under constraints, in the form of normalized boundary potentials. Its application to the neighboring data collection method is presented here. Mathematical models are developed according to specified criteria. These express the reconstructed image in terms of one-dimensional Lagrange multiplier functions. The reconstruction problem becomes one of estimating these functions from normalized boundary potentials. This model is based on a cost criterion of the minimization of the variance between the reconstructed and the true resistivity distributions. The algorithm was tested on data collected in a cylindrical saline-filled tank. A polyacrylamide rod was placed in various positions with or without a peripheral plaster of Paris ring in place. This was intended to resemble the conditions during EIT of epileptic seizures recorded with scalp or cortical electrodes in the human head. One advantage of this approach is that compensation for non-uniform initial conditions may be made, as this is a significant problem in imaging cerebral activity through the skull.
一种用于电阻抗断层成像（EIT）的图像重建新方法已被开发出来。它基于一种约束优化技术，用于在不进行有限元建模的情况下重建差分电阻率图像。它通过在以归一化边界电位形式的约束下优化代价函数来解决逆问题。本文介绍了其在相邻数据采集方法中的应用。根据指定标准开发了数学模型。这些模型根据一维拉格朗日乘子函数来表示重建图像。重建问题就变成了从归一化边界电位估计这些函数的问题之一。该模型基于使重建电阻率分布与真实电阻率分布之间的方差最小化的代价准则。该算法在圆柱形充盐水箱中收集的数据上进行了测试。将一根聚丙烯酰胺棒放置在不同位置，有或没有外周石膏环。这旨在模拟在人头中用头皮或皮层电极记录癫痫发作的电阻抗断层成像过程中的条件。这种方法的一个优点是可以对不均匀的初始条件进行补偿，因为这是通过颅骨成像大脑活动时的一个重大问题。
