Department of Radiology, Hiroshima City General Rehabilitation Center, Hiroshima, Japan.
Magn Reson Med Sci. 2011;10(1):11-9. doi: 10.2463/mrms.10.11.
We evaluated radiofrequency (RF) heating of various implants embedded in a gel phantom during magnetic resonance (MR) procedures. We examined the dependence of RF heating on variation in specific absorption rate (SAR) and angle between the implant and the static magnetic field (B(0)) and on the displacement of the phantom in the irradiation coil using a 1.5-tesla MR system, and we compared the influence of RF heating on the same implant using a 3.0T MR system. Our results support the occurrence of RF heating of implants made of non-magnetizing metal. We observed greater RF heating when the implant was set parallel to B(0), embedded at a shallower depth, and placed at the center of the RF irradiation coil. We also confirmed that the rise in temperature was proportionate to the increase in SAR. We considered the difference in temperature elevation on depth of embedding to reflect the skin-depth effect of RF intensity for both the 1.5- and 3.0-T MR systems.
我们评估了在磁共振（MR）程序期间各种嵌入在凝胶模型中的植入物的射频（RF）加热。我们研究了 RF 加热对吸收率（SAR）和植入物与静磁场（B（0））之间的角度变化的依赖性，以及使用 1.5T MR 系统对模型在辐照线圈中的位移的依赖性，并使用 3.0T MR 系统比较了同一植入物的 RF 加热的影响。我们的结果支持了非磁化金属制成的植入物的 RF 加热的发生。当植入物平行于 B（0）设置、嵌入较浅且放置在 RF 辐照线圈的中心时，我们观察到了更大的 RF 加热。我们还证实，温度升高与 SAR 的增加成正比。我们认为，在嵌入深度上的温度升高差异反映了 1.5 和 3.0-T MR 系统中 RF 强度的趋肤效应。
