Fat suppression by saturation/opposed-phase hybrid technique: spin echo versus gradient echo imaging

The objective of the study was to compare hybrid opposed-phase fat suppressed sequences using gradient-echo (GRE) and spin-echo (SE) techniques. Eight normal volunteers had abdominal imaging at 1.5 T using both an opposed-phase fat-suppressed SE sequence (TR/TE 450/14) and an opposed phase GRE sequence (TE = 2.5) with frequency-selective fat suppression. Signal to noise ratios (SNR) and contrast to noise ratios (CNR) relative to fat of pancreas, liver and paraspinal muscle were calculated for each sequence. The GRE sequence with TR of 150 (25 s breath-hold) significantly outperformed the corresponding 3 min SE sequence for SNR and CNR for all tissues (p < .05). Hybrid opposed-phase fat-suppressed GRE sequences can be performed with breath-holding in less overall imaging time than SE sequences, and can achieve superior fat suppression and signal-to-noise if sufficient TR is used.