title: Consistent fat suppression with compensated spectral-spatial pulses.
abstract: Reliable fat suppression is especially important with fast imaging techniques such as echo-planar (EPI), spiral, and fast spin-echo (FSE) T2-weighted imaging. Spectral-spatial excitation has a number of advantages over spectrally selective presaturation techniques, including better resilience to B0 and B1 inhomogeneity. In this paper, a FSE sequence using a spectral-spatial excitation pulse for superior fat suppression is presented. Previous problems maintaining the CPMG condition are solved using simple methods to accurately program radio-frequency (RF) phase. Next an analysis shows how B0 eddy currents can reduce fat suppression effectiveness for spectral-spatial pulses designed for conventional gradient systems. Three methods to compensate for the degradation are provided. Both the causes of the degradation and the compensation techniques apply equally to gradient-recalled applications using these pulses. These problems do not apply to pulses designed for high-speed gradient systems. The spectral-spatial FSE sequence delivers clinically lower fat signal with better uniformity than spectrally selective pre-saturation techniques.
authors.affiliation: Department of Electrical Engineering, Stanford University, California 94305-4055, USA.
authors.forename: W
authors.initials: W
authors.lastname: Block
authors.forename: J
authors.initials: J
authors.lastname: Pauly
authors.forename: A
authors.initials: A
authors.lastname: Kerr
authors.forename: D
authors.initials: D
authors.lastname: Nishimura
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging