Simulation of SAR and B1+ homogeneity change with subject movement using 16ch transceiver coil at 7T

Motivation: SAR estimation at UHF is critical. Particularly when subject moves during scan, SAR could be changed significantly, potentially exceeding limit. Goal(s): We investigated how SAR and B1+ homogeneity is changed by head movement, coil tunning/matching(TM) and B1+ shim. Approach: Using EM simulation with human model with 16ch transceiver, B1+ and SAR distribution was estimated for different head positions, coil TM and B1+ shim. Results: Head movement is main contributor to SAR increase; but also suboptimal coil TM and B1+ shim contributing to the variation. Impact: Estimation of B1+ and SAR changes by subject motion would improve scan safety as well as B1+ shim approach.