SAR safety procedure for self-built pTx human head RF array coils at 9.4T

Motivation: Ensuring subject safety, in particular to limit tissue heating, is a critical aspect of self-developed pTx RF array coils for UHF applications. Goal(s): Establishing a dependable workflow for accurate simulation, data processing and realization of online supervision of power deposition. Approach: The workflow relies on cross-comparisons of EM simulation results and intermediate processing steps based on representative excitation modes, and on comparison of measured and simulated field maps. Results: Consistency was achieved in all cross-comparison steps. Residual discrepancies between measured and simulated B1+ maps require further investigation, but their safety implications can be addressed by an appropriate safety factor. Impact: A reliable workflow for EM simulation, subsequent data processing, and realization of online SAR monitoring for home-built RF human head array coils at 9.4T is presented. This is an essential building block to ensure subject safety in experimental UHF studies.