Buechler D N, Durney C H, Christensen D A
Department of Electrical Engineering, University of Utah, Salt Lake City 84112, USA.
Magn Reson Imaging. 1997;15(10):1157-66. doi: 10.1016/s0730-725x(97)00179-3.
Electric (E) fields induced near metal implants by MRI switched-gradient magnetic fields are calculated by a new equivalent-circuit numerical technique. Induced E-field results are found for a metallic spinal-fusion implant consisting of two thin wires connected to the metallic case of a current generator as well as for its subsections: a bare U-shaped wire, an insulated U-shaped wire, a cut insulated wire, and a generator. The presence of the metallic implants perturbs the E field significantly. Near the ends of the bare U-shaped wire, the E field is 89.7 times larger than in the absence of the wire. The greatest E field concentration occurs near the ends of the cut insulated wire, where the E field is 196.7 times greater than in the absence of the wire. In all cases, the perturbation of the induced E field by the implanted wire is highly localized within a few diameters of the wire.
通过一种新的等效电路数值技术计算了MRI开关梯度磁场在金属植入物附近感应产生的电场（E场）。对于由连接到电流发生器金属外壳的两根细线组成的金属脊柱融合植入物及其各部分，即裸U形线、绝缘U形线、切断的绝缘线和发生器，均得出了感应E场结果。金属植入物的存在会显著干扰E场。在裸U形线的末端附近，E场比没有该线时大89.7倍。最大的E场集中出现在切断的绝缘线末端附近，此处的E场比没有该线时大196.7倍。在所有情况下，植入线对感应E场的干扰都高度局限于线的几个直径范围内。
