Magnetic-resonance-induced heating of implantable leads

In this study a methodological approach for measuring temperature and local absorption rate (SAR) on thin metallic structures, such as pacemaker (PM) leads, is provided. First preliminary experiments were performed to evaluate the error in temperature and SAR measurements made by fluoroptic temperature probes when the temperature probe is in different contact configuration with the PM lead tip. Our results show how the position of temperature probes affects the temperature and SAR value measured at the lead tip. The transversal contact between the thermal sensor and the lead tip is the configuration which leads to the highest values for temperature and SAR. In the second part of this paper we describe two physical models of a human trunk and an experimental set-up to investigate the influence of the implant geometry and of the lead path on the heating and the local SAR deposition. Experiments reveled that the implant location and configuration are crucial elements for the heat generation at the lead tip.