Fast fat suppression RF pulse train with insensitivity to B1 inhomogeneity for body imaging

Abstract

In higher-field magnetic resonance imaging scanners, a spectrally selective fat saturation radiofrequency (RF) pulse does not work well because B 1 inhomogeneity increases. An adiabatic 180° pulse is used to improve nonuniform fat suppression, but requires inversion recovery time. Therefore, a new RF pulse that achieves flip angles near 90°and is B 1 insensitive has been developed. The pulse consists of three sinc-shaped RF pulses with different flip angles and with different time intervals between each RF pulse. Using the Bloch equations, we analyzed the optimal combination of flip angles. Experimental results demonstrated that Mz was maintained at less than 0.05 M0 for a B1 inhomogeneity of ±35%. The optimal net flip angles was adjusted to 95°by varying the time interval between RF pulses. The pulse duration was 77 ms, which is less than half of the 170-ms inversion recovery time required for the adiabatic pulse. We demonstrated excellent fat suppression for body imaging. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.