Dan Xu1, Kevin F. King1
1Applied Science Laboratory, GE Healthcare, Waukesha, WI, USA
Most existing applications of parallel transmission have been restricted to gradient echo due to lack of systematic design of parallel transmit refocusing pulses. In this paper, we propose a new optimal control based method to design parallel transmit refocusing pulses for spin echo sequences with a single refocusing pulse per repetition time. The method addresses pulse nonlinearity by including Bloch equation in the formulation, designs pulses that refocus a spin ensemble, and optimizes nutation directions to achieve homogenous refocusing. Simulation results show that refocusing pulses designed by the proposed method produce better homogeneity than pulses designed by conventional methods.