Deptartment of Technology and Health, Italian National Institute of Heath, Rome, Italy.
Magn Reson Med. 2012 Apr;67(4):925-35. doi: 10.1002/mrm.23067. Epub 2011 Jul 11.
MRI-induced heating on endocardial leads is a serious concern for the safety of patients with implantable pacemakers or cardioverter-defibrillator. The lead heating depends on many factors and its amount is largely variable. In this study, we investigated the role of those structural properties of the lead that are reported on the accompanying documents of the device: (1) fixation modality (active vs. passive); (2) number of electrodes (unipolar vs. bipolar); (3) length; (4) tip surface; and (5) tip and ring resistance. In vitro temperature and specific absorption rate measurements on 30 leads (27 pacemakers, three implantable cardioverter-defibrillator leads) exposed to the radiofrequency field typical of a 1.5 T MRI scanner are presented. The data show that each lead has its own attitude to radiofrequency-induced heating and that the information that is available in the accompanying documents of the pacemaker is not sufficient to explain such attitude. Even if combined with that of the implant geometry, this information is still not sufficient to estimate the amount of heating due to the exposure to the radiofrequency field during MRI examination.
MRI 诱导的心脏内导线加热是植入式起搏器或除颤器患者安全的严重问题。导线加热取决于许多因素，其数量在很大程度上是可变的。在这项研究中，我们研究了设备随附文件中报告的那些导线结构特性的作用：（1）固定方式（主动与被动）；（2）电极数量（单极与双极）；（3）长度；（4）尖端表面；（5）尖端和环电阻。介绍了在暴露于典型 1.5 T MRI 扫描仪射频场的 30 根导线上进行的体外温度和比吸收率测量（27 根起搏器，三根植入式除颤器导线）。数据表明，每个导线对射频诱导加热都有自己的态度，并且起搏器随附文件中的信息不足以解释这种态度。即使与植入物几何形状相结合，这些信息仍然不足以估计由于在 MRI 检查期间暴露于射频场而导致的加热量。
