Safety assessment of AIMDs under MRI exposure: Tier3 vs. Tier4 evaluation of local RF-induced heating

Patients with active implantable medical devices (AIMDs) are generally excluded from magnetic resonance (MR) diagnostics because interference of the AIMD with MR-induced radiofrequency (RF) fields can lead to hazardous localized heating in the surrounding tissues. In this work, we report the safety assessment of a generic device performed according to tier 3 and 4 guidelines in Technical Specification 10974. For tier 3, local tissue heating was obtained by applying RF fields, obtained numerically in vivo in human models exposed to MRI coils, to a transfer function of the device. For tier 4, a validated model of the generic device was implanted in anatomical human models exposed to the RF of MRI coils, and full-wave computational electromagnetic simulations were performed. A comparison of the two methods is made.