Can B1+RMS help prevent overly restrictive MR Conditional labels for medical devices that are currently based on SAR?

Motivation: The primary RF exposure metric used for MR Conditional labeling of medical devices is whole-body(wb) average SAR, which is typically overestimated by MRI scanners, leading to potentially overly restrictive labels. Goal(s): The purpose of this study was to determine if B1+RMS as an RF exposure limit can help prevent overly restrictive MR Conditional labels. Approach: In-vivo RF-induced heating simulations in a 0.55 T MRI scanner were performed to compare potential labeling at the scanner-reported B1+RMS and wbSAR with the driving voltage maximized. Results: Results depicted a 7-13x decrease in maximum temperature rise when the RF exposure is limited by B1+RMS instead of wbSAR. Impact: The use of B1+RMS to limit RF exposure instead of SAR has significant potential to prevent unnecessarily restrictive MR Conditional labels for medical devices, especially in lower magnetic field strength MRI systems that are incapable of achieving high SAR levels.