Evaluation of MRI RF electromagnetic field induced heating near leads of cochlear implants
Evaluation of MRI RF electromagnetic field induced heating near leads of cochlear implants
复制标题
人工耳蜗引线附近 MRI 射频电磁场感应加热的评估
DOI：
--
复制
发表时间：
2018
影响因子：
3.5
通讯作者：
Ji Chen
中科院分区：
文献类型：
--
作者：
Qi Zeng;Qingyan Wang;Jianfeng Zheng;W. Kainz;Ji Chen
磁共振成像（MRI）程序下的典型耳蜗植入系统可能与射频（RF）电磁场（EMF）耦合，并在导线尖端产生增强的电场。因此，沉积在电极导线头端周围人体组织中的射频能量可能会引起发热并引起组织损伤问题。本研究的目的是评估人工耳蜗植入系统在1.5T MRI线圈中的射频电磁场感应加热，并突出对加热有显著影响的因素。RF-EMF感应加热涉及的潜在因素包括电极导线类型、电极导线轨迹、人体模型和MRI标志。在本文中，三种类型的电极导线的射频电磁场感应加热进行了评估，在两个虚拟人体模型。使用传递函数方法研究了总共24个电极导线轨迹和23个解剖标志位置。人体模型中所有研究病例的平均温升为0.79 °C，RF体线圈中最大全身平均比吸收率为2 W kg−1时的最大值为2.80 °C。研究发现，电极导线轨迹和MRI标志是两个主要影响因素。不同电极导线轨迹的最大温升范围为0.82 - 2.80 °C。当界标从−100 mm变化到700 mm时，观察到2.80 °C的加热差异。这项工作表明，在评估植入式医疗器械的射频电磁场感应加热时，有必要考虑这些因素。
A typical cochlear implant system under magnetic resonance imaging (MRI) procedures may couple with the radio frequency (RF) electromagnetic field (EMF) and results in an intensified electric field at the lead tip. As a result, the RF energy deposited in human tissues around the lead tip may induce heating and cause tissue damage concerns. The purpose of this work is to evaluate the RF-EMF-induced heating for cochlear implant system in 1.5 T MRI coil and highlight the factors that have significant effects on the heating. The potential factors involved in the RF-EMF-induced heating including the lead type, lead trajectory, human model and MRI landmark. In this paper, the RF-EMF-induced heating for three types of leads is evaluated in two virtual human models. A total of 24 lead trajectories and 23 anatomical landmark positions are studied using the transfer function method. The average temperature rise for all the studied cases in the human models is 0.79 °C, and the maximum value is 2.80 °C for a maximum whole-body average specific absorption rate of 2 W kg−1 in an RF body coil. It is found that the lead trajectory and MRI landmark are two primary influencing factors. The maximum temperature rises for different lead trajectories can vary from 0.82 to 2.80 °C. A difference in heating of 2.80 °C is observed when the landmark changes from −100 to 700 mm. This work demonstrates that it is necessary to take these factors into account when evaluating the RF-EMF-induced heating for implanted medical devices.