Multiecho Imaging With Intrinsic Fat Suppression

PURPOSE: To investigate a modification of the RARE(TSE,FSE)-method for chemical shift selective imaging without additional chemical shift selective preparation pulses at high fields. METHODS: The method is based on a standard TSE-sequence, where the excitation pulse is displaced by a time shift of dTE. dTE is set such that fat signal experiences a phase shift by 90° with respect to on resonance spins. As a result, the signal from fat will experience the ensuing echo train as a rapidly decaying CP-echo train, whereas water will show the beneficial CPMG-conditions. RESULTS: Results on human volunteers demonstrate the efficient fat suppression of the TE-shifting especially for T2-weighted imaging of the head at 3 and 5 T. The time shift is sufficiently small to keep the T2-contrast constant. CONCLUSION: TE-shifted TSE has demonstrated to be an efficient method for fat suppression without the need of additional fat suppression pulses. The fat suppression scheme is largely independent of the actual flip angles used and thus very robust against B1-inhomogeneities. The method is sensitive to B0-inhomogeneities, which limits its usefulness outside of the head.