Abstract #3869

Optimization of Composite Pulses Considering Pulse Duration, Excitation Uniformity & SAR

Bu S. Park^1,2, J. McGarrity², Z. Cao², K. Sung³, S. Oh², C. M. Collins²

¹NIH, Bethesda, MD, United States; ²Radiology, the Pennsylvania State University, Hershey, PA, United States; ³Radiology, Standford University, Stanford, CA, United States

Except for RF shimming, transmit array pulses are generally expected to require more time than their quadrature-drive, single-pulse counterparts. Although many transmit array pulses can achieve better excitation uniformity than a simple pulse (including RF shimming), to do so in the same time duration with no significant increase in SAR is a challenge. Here we explore the effect of pulse duration in an array-optimized composite pulse (ACP) and in RF shimming designed to both improve excitation uniformity in the whole brain and reduce SAR using an 8-channel transmit head array, and compare results with the conventional quadrature drive at 7T. Minimum RF excitation time having better excitation uniformity and less SAR than the conventional quadrature drive for each pulse is presented.