Refine Phase Modulation Function Sampling Step Size in Off-Center Variable-Rate Selective Excitation with Rf Pulse Magnitude Replication

Leping Zha¹, Mitsue Miyazaki¹

Optimized rf waveforms are often designed under the hard pulse approximation, and come with a small number of wave points and singular features. When the original designs are converted to variable-rate pulses, the small number of points often causes the often required variable-rate phase modulation function to be inadequately sampled, resulting in selection profile degeneration in off-center slices. The piece-wise-constant amplitude function should be preserved, with the proposed simple pulse magnitude replication method which enables much finer phase sampling step size to better mimic the continuous phase function, and to help maintain the selection quality of the original pulse design.