Local SAR comparison of leg positioning in 16-channel proton/sodium dipole/loop array for 7T MRI

Motivation: Sodium(23Na)/proton(1H) MRI of the extremities have great potential in diagnosis and treatment of musculoskeletal conditions and oncology applications (e.g.soft-tissue sarcomas). Goal(s): Assessing the performance of a novel 16-channel 1H/23Na MRI coil across varied leg positions and establish safe RF power limits for clinical applications. Approach: Electromagnetic simulations to analyse coil performance in four leg positions. SAR10g levels were compared across configurations while maintaining B1+ field efficacy. Results: The coil showed consistent B1+ performance across all tested positions. The highest SAR levels occurred with calf-to-coil contact, aligning with predictions. Safe RF power limits were established, supporting the coil's clinical potential for extremity imagingImpact: This study validates an innovative 16-channel 1H/23Na coil, setting benchmarks for safe RF power limits, and enhancing disease characterisation, enabling clinical research in musculoskeletal pathologies and soft-tissue sarcoma in the extremities.