Spectrally selective suppression with steady-state free precession

Abstract

A method that exploits the intrinsic selectivity of steady-state free precession (SSFP) to perform spectral suppression is disclosed. Such a method avoids the need to incorporate additional spectrally selective pulse sequence elements. The scheme is based on breaking the FISP imaging sequence into short trains having, for example, 8–64 RF pulses. At the moment of echo formation (i.e., TE=TR/2) after the last full RF pulse of the train, water signal is z-stored. Residual transverse magnetization, which include isochromats phase-opposed to the on-resonance water, is gradient crushed and RF spoiled. The stored magnetization is subsequently re-excited with little disturbance to the on-resonance steady-state water signal. The additional time required to perform the steady-state interruption is typically as little as a single TR, minimally affecting the efficiency of the imaging process. The sequence can be employed repetitively, greatly reducing the amplitude of fat signals throughout a real-time or cine imaging process.

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