TISSUE HEATING DUE TO ENDOCARDIAL LEADS DURING MRI SCANS Numerical Models and Experimental Validation

Magnetic Resonance Imaging (MRI) tissue heating due to implanted leads represents a major concern for the safety of patients bearing metallic devices. In this work temperature measurements were performed to validate the typical solutions adapted as endocardial lead models, that are a thin bare metal wire and an insulated one. Both experimental and numerical analysis was performed in the frequency range between 10kHz and 128MHz ( frequencies of the gradient and RF fields of MRI systems). We found that the bare wire is not a reliable model to study the RF heating locally induced at the lead tip. At low frequencies (<1MHz), the PM lead can be properly modelled as an insulated thin metal wire, providing that the actual resistivity of the lead is also modelled. As frequency increases, such a model becomes less accurate and different solutions must be adopted.