On the combination of simulations from various human models to account for variabilities while limiting SAR10g overestimation for UHF pTx MRI

Motivation: Reports highlight variability in 10g-averaged specific absorption rate (SAR10g) when varying subjects and radiofrequency coil position, necessitating safety factors to prevent underestimation, leading to overconservative SAR constraints. Goal(s): To provide a method for selecting appropriate body models to balance RF safety and sequence performance, while investigating SAR10g variability in 7T spinal cord pTx MRI. Approach: The impact of tissue properties, anatomy, body-mass index, and coil positioning on SAR10g was evaluated according to multiple metrics. Results: The mean absolute percentage error can complement the safety factor to decrease SAR10g overestimation and guide the choice of human models used for SAR-monitoring. Impact: Simulations of local-SAR in generic human models are widely used to ensure RF safety at 7T. We show that optimizing the choice of models used for SAR-monitoring may lead to less conservative SAR-constraints, which may improve sequence and pTx performance.