Evaluation of RF heating due to various implants during MR procedures.

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.