A modified multi-echo AFI for simultaneous B sub(1) super(+) magnitude and phase mapping super()

To simultaneously acquire the B sub(1) super(+) magnitude and B sub(1) super(+) phase, a modified multi-echo actual flip-angle imaging (AFI) sequence is proposed. A multi-echo gradient echo sequence was integrated into every even TR of AFI to measure both magnitude and phase of B sub(1) super(+). In addition, to increase the signal-to-noise ratio of the B sub(1) super(+) phase, a double-angle multi-echo AFI sequence, in which the flip-angle of the RF pulses is alpha at the odd TR and 2 alpha at the even TR is proposed. Images were simulated to evaluate the performance of this method under various imaging and physical parameters. The performance was compared to the spin echo based B sub(1) super(+) mapping method in phantom and in vivo studies.