3D stack-of-blades spin echo

A slab-selective excitation and 180-degree refocusing pulse form one spin echo, followed by a PROPELLER line with Cartesian partition encoding. Spoilers suppress unwanted coherence between repetitions. TE and TR determine T2 and longitudinal recovery weighting. The overlapping blade centres support motion-robust 3D structural imaging.

Sixteen-line blades

Sixteen lines per blade, at every partition.

import pypulseqpp as pp
from pypulseqpp.sequences import se_stack_of_blades3D_sequence

baseline = se_stack_of_blades3D_sequence(
    n=96, n_z=8, blade_width=16, te=None, tr=None, n_dummy=0
)
print(f"{baseline.num_blocks} blocks, {baseline.duration()[0]:.2f} s")

11520 blocks, 16.38 s

Sequence diagram

baseline.paper_plot()

Sampling order

The blades of every partition, over the three k-space axes.

pp.plot.plot_kspace(baseline, color_by="shot")

Wider blades

Increasing blade width reduces the number of orientations and increases the shared central-k-space region.

alternative = se_stack_of_blades3D_sequence(
    n=96, n_z=8, blade_width=32, te=None, tr=None, n_dummy=0
)

                   blocks  duration (s)  acquisitions
16 lines            11520         16.38          1280
32 lines            11520         16.38          1280

pp.plot.plot_kspace(alternative, color_by="shot")