B inhomogeneity-insensitive triple-quantum-filtered sodium imaging using a 12-step phase-cycling scheme.

Triple-quantum-filtered (TQF) sodium MRI can be used to separate sodium NMR signals from different physiological compartments. Although three-pulse triple-quantum filtering has been demonstrated to be better suited for in vivo imaging, the absence of the refocusing pulse in the filter increases its sensitivity to magnetic field inhomogeneities. Therefore, several TQF cycles have been developed previously to correct image distortions caused by B(0) inhomogeneities. In this paper, we present a new 12-step phase-cycling TQF scheme based on three radiofrequency pulses which allows the compensation of B(0) variations both with and without ancillary B(0) map information. The method offers 40% higher signal-to-noise-ratio efficiency compared with the previously developed B(0)-correcting phase-cycling schemes.