Simultaneous multi-slice imaging reduces sensitivity of local-SAR to patient motion at 7T

This study investigates the effect of within-scan patient motion on local-SAR for simultaneous multi-slice (SMS) imaging at 7T. A virtual body model was simulated at 104 different positions. 1-/2-/3-spokes pulses were designed to excite a region of 60 slices covering the cerebellum and the brain, using SMS-factors of 1 through 5. Local-SAR was observed to increase by up to 2.75-fold due to patient motion. Pulses with higher SMS-factors were up to 50% less sensitive against changes in local-SAR due to patient motion, compared to SMS:1 pulses. Pulses with higher SMS-factors yielded more consistent local-SAR throughout the scan.