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. Author manuscript; available in PMC: 2019 May 1.
Published in final edited form as: J Magn Reson. 2018 Mar 3;290:18–28. doi: 10.1016/j.jmr.2018.03.002

Figure 1.

Figure 1

Top: RF and gradient waveforms for a 2D RF Pulse. The inset shows a zoomed-in portion of the pulse showing detail of a RF hard-pulse train interleaved with short gradient pulses. The hard-pulse amplitudes follow a Gaussian weighting. Note that each hard pulse samples a unique location in excitation k-space. Bottom Left: A 2×2 sub-pulse train used in a 2D PSF-Choice implementation. Amplitudes of the 4 RF pulses and the gradients, Phx and Phy, are set on each of the 8×8 encoding steps (shots). The PSF-Choice encoding scheme is designed so that each of the 256 excitation k-space locations (4×8×8) is sampled over the course of 64 shots (with 4 locations per shot). The time scales for the RF diagrams are in arbitrary units included only to show the relative duration of the RF trains for the PSF-Choice RF pulse train compared to the full 2D pulse train. Bottom Right: Excitation k-space representation for the 2D RF pulse. The RF pulse train for PSF-Choice consists of a subset of 4 hard pulses (α11, α12, α21 and α22) sampling 4 excitation k-space locations on each of 64 shots (with shot number as indicated for the first 10 shots). The locations in excitation k-space sampled by the 4 pulses are represented by the red, blue, green and purple colored dots respectively. Amplitude settings for the pulses are represented by height of the mesh plot, giving an overall Gaussian weighting across the excitation k-space.