Liu Feng, Zhao Huawei, Crozier Stuart
The School of Information Technology and Electrical Engineering, The University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia.
IEEE Trans Biomed Eng. 2003 Jul;50(7):804-15. doi: 10.1109/TBME.2003.813538.
Prior theoretical studies indicate that the negative spatial derivative of the electric field induced by magnetic stimulation may be one of the main factors contributing to depolarization of the nerve fiber. This paper studies this parameter for peripheral nerve stimulation (PNS) induced by time-varying gradient fields during MRI scans. The numerical calculations are based on an efficient, quasi-static, finite-difference scheme and an anatomically realistic human, full-body model. Whole-body cylindrical and planar gradient sets in MRI systems and various input signals have been explored. The spatial distributions of the induced electric field and their gradients are calculated and attempts are made to correlate these areas with reported experimental stimulation data. The induced electrical field pattern is similar for both the planar coils and cylindrical coils. This study provides some insight into the spatial characteristics of the induced field gradients for PNS in MRI, which may be used to further evaluate the sites where magnetic stimulation is likely to occur and to optimize gradient coil design.
先前的理论研究表明，磁刺激所诱发电场的负空间导数可能是导致神经纤维去极化的主要因素之一。本文研究了在磁共振成像（MRI）扫描期间，时变梯度场诱发的外周神经刺激（PNS）的这一参数。数值计算基于一种高效的准静态有限差分方案以及一个符合解剖学实际的人体全身模型。已对MRI系统中的全身圆柱形和平板梯度集以及各种输入信号进行了探索。计算了诱发电场及其梯度的空间分布，并尝试将这些区域与已报道的实验刺激数据相关联。平面线圈和圆柱形线圈的诱发电场模式相似。本研究为MRI中PNS诱发场梯度的空间特性提供了一些见解，这可用于进一步评估可能发生磁刺激的部位，并优化梯度线圈设计。
