Impacts of RF shimming on MRI induced heating of implantable medical lead in 3T birdcage coil

Transfer function method was utilized to evaluate the RF-induced heating of implantable lead with 137 implanted lead trajectories under different shimming conditions. A coated wire is used to emulate medical leads. Two different shimming conditions were studied. One is to optimize the homogeneity of the B_(1+) field magnitude in human heart region, and second one is to estimate the possible worst-case of the RF field induced heating. All the results are normalized to 2W/kg average whole body specific absorption rate (SAR) and Q-Matrices formalism method was used to improve the SAR calculation efficiency. The average temperature rise at the lead tip under Quadrature excitation is 6.28°C while the RF shimmed homogeneous condition leads to 11.7 °C in temperature rise. The absolutely worst-case RF induced heating is at 61.6°C. As the results suggested, significant impacts on RF-induced heating due to RF shimming were observed.