Comparison of lead electromagnetic model and 3D em results for helix and straight leads

This case study investigates the difference in the RF-induced power deposition (P) for helix and straight leads at 127.7 MHz obtained with the lead electromagnetic model (LEM) and direct 3D electromagnetic (EM) simulations. A large set of incident electric fields was generated in a phantom by an array of four antennas with varying spatial positions and sources. We found discrepancies between the LEM and the 3D EM results, which are up to an order of magnitude higher for the helix lead compared to the straight lead. The results are raising doubts about the applicability of the LEM method for radiofrequency (RF) induced heating of any active implantable medical devices (AIMDs) during magnetic resonance imaging (MRI) exposure.