Alternating TE Radial Sequence for Inherent Fat Suppression

Several fat suppression techniques have been developed for MR pulse sequences. Unfortunately, these techniques require additional acquisition time either for specialized RF excitation pulses (i.e. binomial, STIR, CHESS) or for additional k-space acquisitions (e.g. Dixon Methods). Longer acquisition times limit the use of these techniques for fast or real-time MR applications such as cardiacimaging. In this study, a steady-state radial sequence was developed with alternating echotimes (TE) between even (in-phase) and odd (out-of-phase) k-space projections, similar to the 2-point Dixon methods and the recent Spider sequence. The fat signal is inherently suppressed as the fat phase variation destructively combines to produce a reduced fat signal amplitude in the central portion of k-space. This new fat suppression method provides high water SNR and fat suppression equivalent to the 2-point radial Dixon methodwith a significant reduction in "streak" artifacts.

Water and fat phantom images from a standard FLASH sequence (TE = 6.6ms), 2-point Dixon (TE = 6.6/8.8ms) and a radial alternating TE sequence (TE = 6.6/8.8ms). The streak artifacts in the AltTE image are decreased relative to the 2-point Dixon image.