ANALYTICALLY OPTIMIZED FREQUENCY-MODULATION FUNCTIONS FOR ADIABATIC PULSES

A new method is presented for generating analytic modulation functions for pulses that are insensitive to the radiofrequency field inhomogeneities over a predefined range of the RF field variations. This method is based on determining the relationship between the amplitude- and frequency-modulation functions that is required to satisfy the adiabatic condition over a given range of the RF field variations. This relation can be used to optimize existing modulation functions for adiabatic pulses to improve their insensitivity to the RF field inhomogeneities. It can also be used to generate new modulation functions for adiabatic pulses. The improved performance of the resulting modulation functions was confirmed by computer simulations and demonstrated by experiments on phantoms. © 1991.