Figure 2.

3D multi-echo UTE Cones k-space sampling trajectory with the golden-ratio re-ordering. In (a) and (b), 15 conical surfaces spanning from the “south” to the “north” pole of the k-space are displayed. These surfaces were subsampled at every 15th conical surface from the south to the north pole out of the total 211 conical surfaces determined by a given FOV and resolution. The number of cone interleaves on these surfaces are determined to meet the Nyquist sampling criterion based on the readout duration, then these cone interleaves are re-ordered using the golden-ratio permutation as displayed in (c). The gradient waveforms shown in (d) are associated with the cone interleaf in red in (a), (b), and (c), where 6 echoes are acquired with two shots and an echo train length of 3 in a time-interleaved fashion. Readout duration of each cone interleaf is ~1 ms.