Accurate assessment of 11.7 T head coil energy deposition using field-drift tolerant proton resonance frequency-based MR thermometry

Motivation: RF transmit safety for high-field MRI. Goal(s): Validation of RF heating simulations for a human head transmit/receive coil for 11.7 T using high-sensitivity field-drift tolerant MR thermometry. Approach: Isopropanol was added to a polyvinylpyrrolidone head phantom to serve as an internal reference for MR thermometry. This phantom was used to compare the RF energy deposition by a 500 MHz head coil with FDTD simulations. Results: Temperature precision better than 20 mK was achieved. Correspondence between temperature maps and SAR prediction from FDTD simulations demonstrated validity of the approach for high-field coil safety assessment. Impact: A state-of-the-art method for high-field transmit coil performance assessment is presented: High-accuracy FDTD simulation of SAR deposition from a 500 MHz human head coil was validated using a robust MR thermometry method, based on an internally-referenced phantom material.