spiral TSE seq file not properly simulating

[mzaiss]

spiralTSE.seq.txt

create from

https://github.com/HennigJue/single-shot-spiral-TSE

[J-Endres]

1. The importer doesn't know the pulse usage

The plotted k-space (as well as the reconstruction) needs to know which pulses are used for refocusing and which for excitation. This is guessed using the flip angle, assuming that all pulses > 90° are for refocusation. The spiral TSE sequence uses lower flip angles, so when calculating the k-space trajectory some pulses are wrongly accused to be excitation pulses.

Fix, insert after loading the sequence:

for rep in seq0[3:]:
    rep.pulse.usage = mr0.PulseUsage.REFOC

After that, the readout is centered correctly (doesn't change the simulation which always considers all paths):

2. Wrong gradients

This has still to be investigated: The spiral doesn't look very homogeneous. But more important: z-gradients seem to be wrong

The simulation generates no signal because only a single slice is simulated, where magnetization is spoiled because the readout trajectory is not on z=0

[mzaiss]

ok, i try to recreate the seq files without z grad

[J-Endres]

The new importer in mr0 v2.6 will solve this, closing this issue

[mzaiss]

proof:

[mzaiss]

ok