Riera J J, Fuentes M E
Department of Neurophysics, Cuban Neuroscience Center, Cubanacán, Havana, Cuba.
IEEE Trans Biomed Eng. 1998 Jun;45(6):746-53. doi: 10.1109/10.678609.
A new method is presented for computing the electric lead field of a realistic head shape model which has piecewise homogeneous conductivity. The basic formulae are derived using the well-known reciprocity theorem. Previously described methods are also based upon this theorem, but these first calculate the electric potential inside the head by a scalar boundary element method (BEM), and then approximate the ohmic current density by some sort of gradient. In contrast, this paper proposes the direct evaluation of the ohmic current density by discretizing the vector Green's second identity which leads to a vector version of BEM. This approach also allows the derivation of the same equations for the three concentric spheres model as obtained by Rush and Driscoll [8]. The results of simulations on a spherical head model indicate that the use of a vector BEM leads to an improvement of accuracy in the computation of the ohmic current density with respect to those reported previously, in term of different measures of error.
本文提出了一种计算具有分段均匀电导率的真实头部形状模型的电导联场的新方法。基本公式是利用著名的互易定理推导出来的。先前描述的方法也基于该定理，但这些方法首先通过标量边界元法（BEM）计算头部内部的电势，然后通过某种梯度近似欧姆电流密度。相比之下，本文提出通过离散矢量格林第二恒等式直接评估欧姆电流密度，这导致了矢量版本的边界元法。这种方法还可以推导出与拉什和德里斯科尔[8]所得到的相同的三个同心球模型的方程。在球形头部模型上的模拟结果表明，就不同的误差度量而言，使用矢量边界元法相对于先前报道的方法在计算欧姆电流密度时精度有所提高。
