Akter Mir Khadiza, Shen Ao, Islam Md Zahidul, Zheng Jianfeng, Steckner Michael, Chen Ji
Department of Electrical and Computer Engineering, University of Houston, Houston, Texas, USA.
MKS Consulting, Beachwood, Ohio, USA.
Magn Reson Med. 2025 Oct;94(4):1714-1730. doi: 10.1002/mrm.30578. Epub 2025 May 23.
To investigate the implications of lateral patient position on radiofrequency (RF)-induced heating of active and passive implantable medical devices (AIMDs and PIMDs) in a wide-bore 3T MRI system.
In vitro simulations for two rod positions and three lateral phantom shifts were experimentally validated inside a wide-bore 3T MRI scanner. Three commercially available AIMDs (40-cm peripheral nerve stimulator [PNS], 45-cm restorative neurostimulator, and 50-cm cardiac rhythm management system) were analyzed. RF-induced heating for AIMDs was assessed using the transfer function method, which combines transfer functions with tangential electric fields along clinically relevant device pathways for the Duke, Ella, and Fats human body models. Thirty-minute temperature rises were numerically simulated near four orthopedic PIMDs (shoulder, hand-wrist plate, femoral plate, hip replacement) inside human body models.
RF-induced heating of the titanium rod varied with lateral phantom shifts due to changes in electric-field distribution. Centrally positioned cardiac rhythm management and restorative neurostimulator devices exhibited less than 4°C and 1°C 95th percentile temperature rise variation, respectively. Meanwhile, some PNS devices, due to their peripheral placement in regions with varying electric-field exposure, showed up to 8.8°C variation in 95th percentile temperature rise. Similarly, 1-g mass-averaged specific absorption rate near PIMDs increased by up to 50 W/Kg, and a 19.7% increase in temperature rise is noted.
The increased flexibility in lateral patient position within wide-bore MRI can increase RF-induced heating with implications for MR conditional labeling, especially for PNS devices and PIMDs.
研究在宽孔径3T磁共振成像（MRI）系统中患者侧卧体位对主动和被动植入式医疗设备（AIMD和PIMD）的射频（RF）感应加热的影响。
在宽孔径3T MRI扫描仪内对两种棒位置和三种横向体模偏移进行体外模拟，并通过实验验证。分析了三种市售的AIMD（40厘米外周神经刺激器[PNS]、45厘米恢复性神经刺激器和50厘米心脏节律管理系统）。使用传递函数方法评估AIMD的RF感应加热，该方法将传递函数与沿Duke、Ella和Fats人体模型临床相关设备路径的切向电场相结合。在人体模型内靠近四种骨科PIMD（肩部、手腕板、股骨板、髋关节置换）处对30分钟的温度升高进行了数值模拟。
由于电场分布的变化，钛棒的RF感应加热随横向体模偏移而变化。位于中心位置的心脏节律管理和恢复性神经刺激器设备在第95百分位数温度升高变化分别小于4°C和1°C。同时，一些PNS设备由于其在电场暴露不同区域的周边放置，在第95百分位数温度升高时显示出高达8.8°C的变化。同样，PIMD附近的1克质量平均比吸收率增加高达50 W/Kg，温度升高增加了19.7%。
宽孔径MRI中患者侧卧体位灵活性的增加会增加RF感应加热，这对MR条件标签有影响，特别是对于PNS设备和PIMD。
