Large Tip Angle Segmented RF Design for Multi-Dimensionally Selective Imaging & Spectroscopy with Parallel Transmit

Martin Haas¹, Jeff Snyder¹, Peter Ullmann², Jrgen Hennig¹, Maxim Zaitsev¹

Multi-dimensionally selective RF excitation suffers from artifacts related to the typically long pulse duration. In particular, applications in MR spectroscopy would significantly benefit from shorter pulses due to increased bandwidth. Previous approaches to mitigate this problem using segmented selective excitation across several repetitions have been limited to small tip angles. In this work, a segmented RF design algorithm for large tip angle pulses, with additional parallel transmit acceleration, is described for multi-dimensionally selective excitation and demonstrated in simulations and a phantom. The method is based on a segment-wise optimal control optimization and not limited to 2D or a particular segmentation.