MRI in patients with implantable devices: A numerical model for the evaluation of lead heating

The radiofrequency (RF) field used in magnetic resonance imaging (MRI) procedures may lead to significant increase in temperature and local specific absorption rate (SAR) for patients with implanted pacemaker (PM). In this paper two numerical models were developed to reproduce the heat generation process which occurs at the lead tip of an implanted PM when exposed to a RF field: the former (thermal model) shows how the position of temperature probes definitely affects the estimation of temperature rise and SAR value measured on the lead tip. The transversal contact between the active portion of the probe and the lead tip is the configuration associated with the highest estimation of temperature and SAR, whereas other configurations may lead to an underestimation close to 15% and 70% for temperature and SAR, respectively. The letter (RF model) predicted higher temperature increase and SAR value for right pectoral implants compared to left ones.