Fig. 1.
Scheme of the proposed t-Blipped SMS-MRF acquisition for an acquisition with MB=2. (a) the RF pulse train used in the IR-trueFISP sequence on which the MRF acquisition is based. The inversion pulse is non-selective but each subsequent RF pulse is a multi-band RF which simultaneous excites 2 slices. (b) Detail of the slice selection with VERSE during the RF and the t-Blipped method of imposing phase shifts on the different slice positions of the excited slices in one TR. Here in this MB=2 acquisition, Ablip is the area added to the normal prephasing lobe to provide a phase difference of pi to simultaneously excited slices in the even numbered TRs. This blip area is rewinded after the readout. No blip is added on the odd numbered TRs, creating a zero phase difference between the slices. Signal is read out using spiral trajectory.(c) One of 48 highly under-sampled (48X) variable density spiral interleaves is used in each TR, and corresponding ring-like PSFs plotted.