Calculation of MRI-induced heating of an implanted medical lead wire with an electric field transfer function
Calculation of MRI-induced heating of an implanted medical lead wire with an electric field transfer function
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DOI：
10.1002/jmri.21159
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发表时间：
2007-11-01
影响因子：
4.4
通讯作者：
Nyenhuis, John A.
中科院分区：
文献类型：
--
作者：
Park, Sung-Min;Kamondetdacha, Rungkiet;Nyenhuis, John A.
目的：开发并演示一种方法来计算MRI中射频（RF）场在植入式医疗电极导线电极处引起的温升。材料和方法：通过积分切向电场和沿导线长度沿着的传递函数的乘积来计算电极附近的电场。用矩量法对传递函数进行了数值计算。在64 MHz下计算了不同长度的模型植入物的形式的裸电线和绝缘电线与1厘米的电线暴露在一个或两个end.Results：在电极处的加热取决于大小和相位分布的传递函数和入射电场沿着的长度的铅的传递函数和绝缘电线的传递函数。对于均匀电场，当电极导线端接开路时，电极导线长度约为半个波长时，电极加热最大。加热可以更大的最坏情况下的相位分布的入射field.Conclusion：传递函数提出了一种有效的方法来计算MRI诱导加热的电极的医疗铅。体模中模型植入物的实测温升与传递函数预测的温升非常一致。传递函数可以通过数值或实验确定。
Purpose: To develop and demonstrate a method to calculate the temperature rise that is induced by the radio frequency (RF) field in MRI at the electrode of an implanted medical lead.Materials and Methods: The electric field near the electrode is calculated by integrating the product of the tangential electric field and a transfer function along the length of the lead. The transfer function is numerically calculated with the method of moments. Transfer functions were calculated at 64 MHz for different lengths of model implants in the form of bare wires and insulated wires with 1 cm of wire exposed at one or both ends.Results: Heating at the electrode depends on the magnitude and the phase distribution of the transfer function and the incident electric field along the length of the lead. For a uniform electric field, the electrode heating is maximized for a lead length of approximately one-half a wavelength when the lead is terminated open. The heating can be greater for a worst-case phase distribution of the incident field.Conclusion: The transfer function is proposed as an efficient method to calculate MRI-induced heating at an electrode of a medical lead. Measured temperature rises of a model implant in a phantom were in good agreement with the rises predicted by the transfer function. The transfer function could be numerically or experimentally determined.