FIG. 5.
Top: DS-HPFSE sequence. Two slab selective RF excitations (90x°-180y°) used to produce an echo from the rectangular beam of transverse magnetization at their intersection, followed by a non-selective FSE train to elicit subsequent echoes, encoding them in all three dimensions. Parasitic FID dephasing gradient crushers are built into the readout gradient wings. Bottom plot: Magnetization pathways emerging from the slab selective excitations, and subsequent phase evolution of desired pathway through 3 hard refocusing excitations (180y°). Diagonal lines indicate spin phase under fixed field inhomogeneity (or constant gradient), and horizontal dashed lines indicate evolution of spin magnetization stored along the longitudinal axis.