功能磁刺激中线圈的改进

Improvement of Coils Used in Functional Magnetic Stimulation.

目的改进功能磁刺激中的线圈 ,解决影响线圈刺激特性的主要因素 :兴奋点的确定和聚焦性。方法用法拉第定律计算线圈的感应电场分布。结果当神经和 8字形线圈的手柄垂直 ,并且和线圈边缘相切时 ,感应电场的一阶导数极大值点不随线圈的半径和刺激深度变化 ;用组合线圈可以减小目标点以上区域电场的一阶导数值。结论对于 8字形线圈 ,和传统的刺激方法相比 ,使用新方法易于确定兴奋点位置 ;

Objective Functional magnetic stimulation(FMS) is a new te chnique for stimulating the excitable tissue. But the difficulty to locate the a ctivation point and the poor capability of focusing limit the further progress o f FMS. A new stimulation method using 8-shaped coil and a combinatorial coil we re presented to improve coils performance. Method The distribution o f the induced electrical field was calculated based on Faraday law. Result When the nerve was perpendicular to the handle of 8-shaped coil and tan gential to the coil edge, the position with the maximum of first spatial gradien t of the field did not change with the varying of the radius of coil and the exc itation depth;the values of the first spatial gradient of field above the stimu lation target decreased obviously using the combinatorial coils. Conclusio n Comparing with the current stimulation method of 8-shaped coil, the ne w method gave a fixed activation point. The capability of focusing was improved using the presented combinatorial coil.