FIGURE 1:

3D MRSI pulse sequences. (a) The five building blocks: (i) echo-planar imaging (EPI) navigator for real-time motion correction and shim update; (ii) hypergeometric single band (HGSB) inversion recovery fat suppression; (iii) water suppression enhanced through T₁ effects (WET); (iv) adiabatic spin-echo; (v) either spiral-out or spiral-out-in trajectories (blue arrows). The spiral gradient waveforms for spatial-spectral encoding with a readout time of 320 msec are shown for (b) spiral-out and (c) spiral-out-in. The gray areas indicate rewinder regions. AHP: adiabatic half passage; GOIA: gradient offset independent adiabatic.