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Abstract #2898

B1+ Inhomogeneity Compensation using 3D Parallel Excitation is Enhanced by Simultaneous Linear & Nonlinear Gradient Encoding

William A. Grissom1, Laura Sacolick1, Mika W. Vogel1

1GE Global Research, Munich, Germany

3D parallel spokes excitation pulses have been proposed for compensating flip angle inhomogeneities induced by inhomogeneous B1+ at high field. While flip angle homogeneity improves with increasing spokes pulse duration and an increasing number of parallel excitation channels, competing desires to limit off-resonance sensitivity and system complexity limit these pulses' effectiveness in practice. We show that nonlinear gradient phase encoding is well-suited to this application and that simultaneous linear and nonlinear phase encoding can significantly improve spokes pulse performance, enabling shorter pulse durations and fewer transmit channels for a desired level of flip angle homogeneity.