Fat signal suppression for coronary MRA at 3T using a water-selective adiabatic T2-preparation technique

Abstract

Purpose To improve fat saturation in coronary MRA at 3T by using a spectrally selective adiabatic T2-Prep (WSA-T2-Prep). Methods A conventional adiabatic T2-Prep (CA-T2-Prep) was modified, such that the excitation and restoration pulses were of differing bandwidths. On-resonance spins are T2-Prepared, whereas off-resonance spins, such as fat, are spoiled. This approach was combined with a CHEmically Selective Saturation (CHESS) pulse to achieve even greater fat suppression. Numerical simulations were followed by phantom validation and in vivo coronary MRA. Results Numerical simulations demonstrated that augmenting a CHESS pulse with a WSA-T2-Prep improved robustness to B1 inhomogeneities and that this combined fat suppression was effective over a broader spectral range than that of a CHESS pulse in a conventional T 2-Prepared sequence. Phantom studies also demonstrated that the WSA-T2-Prep+CHESS combination produced greater fat suppression across a range of B1 values than did a CA-T2-Prep+CHESS combination. Lastly, in vivo measurements demonstrated that the contrast-to-noise ratio between blood and myocardium was not adversely affected by using a WSA-T2-Prep, despite the improved abdominal and epicardial fat suppression. Additionally, vessel sharpness improved. Conclusion The proposed WSA-T2-Prep method was shown to improve fat suppression and vessel sharpness as compared to a CA-T2-Prep technique, and to also increase fat suppression when combined with a CHESS pulse. Magn Reson Med 72:763-769, 2014. © 2013 Wiley Periodicals, Inc.