Measurements and simulation of RF heating of implanted stereo-electroencephalography electrodes during MR scans
Measurements and simulation of RF heating of implanted stereo-electroencephalography electrodes during MR scans
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DOI：
10.1002/mrm.27144
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发表时间：
2018-10-01
影响因子：
3.3
通讯作者：
Martens, Michael
中科院分区：
文献类型：
--
作者：
Bhusal, Bhumi;Bhattacharyya, Pallab;Martens, Michael
目的：为了评估植入立体脑电图electroencephalography electrodes.Methods：模拟和实验测量使用体模和头部只有发射/接收线圈上的3 T MR系统进行评估的8接触立体脑电图电极和绝缘导线部分浸入体模的尖端温度升高。导线产生最大（谐振条件）和最小（反谐振条件）加热的长度进行了评估，为不同的进入模式和穿透depth.Results：对于导线和立体脑电图电极，谐振长度接近奇数整数倍的RF四分之一波长在空气中和反谐振长度接近偶数整数倍的RF四分之一波长，都不受进入模式。在共振条件下，温度增加了多达10倍，高于在反共振条件。较大的穿透深度并没有改变谐振长度，但确实导致增加RF heating.Conclusion：对于部分浸没的植入物，如立体脑电图电极，谐振长度被发现是独立的穿透深度和进入模式，虽然温度的增加可能会有所不同。避免这种长度的电缆可以降低体内MRI期间组织加热的风险。
Purpose: To assess RF-induced heating during MRI of patients with implanted stereo-electroencephalography electrodes.Methods: Simulations and experimental measurements using phantom and a head-only transmit/receive coil on a 3T MR system were performed to evaluate temperature increases at the tip of an 8-contact stereo-electroencephalography electrode and an insulated wire partially immersed into the phantom. The lengths of wire producing maximum (resonant condition) and minimum (anti-resonant condition) heating were evaluated for different entry modes and penetration depths.Results: For both wire and stereo-electroencephalography electrode, resonant lengths were close to odd integral multiples of RF quarter wavelength in air and antiresonant length close to even integral multiples of RF quarter wavelength, both being unaffected by the entry mode. In the resonant condition, temperature increased by as much as a factor of 10 higher than that at antiresonant condition. Larger penetration depths did not change resonant length, but did lead to increased RF heating.Conclusion: For the partially immersed implants like stereo-electroencephalography electrode, the resonant lengths were found to be independent of the penetration depths and entry modes, although the temperature increases may vary. Avoiding such lengths of cables can reduce the risk of tissue heating during in vivo MRI.