Issue with RF excitation Times

[cmwalker]

I am having issues with my RF pulses getting offset based on their center time. I suspect that something Changed in how .seq files store the RF pulses and that has caused an issue.

Details:
I cannot get my excitation pulses to align in time with the slice gradients. As you can see below there is an offset between the excitation and the slice gradient. This offset is not seen in the matlab plot of the .seq file

The amount of offset is equal to the 1/2 the pulse duration. i have checked this by changing my pulse length.

If you look at the .seq file you can see there are two times stored for RF pulses, the center and the delay
"
Format of RF events:
id ampl. mag_id phase_id time_shape_id center delay freqPPM phasePPM freq phase use
.. Hz .. .. .. us us ppm rad/MHz Hz rad ..
Field 'use' is the initial of: excitation refocusing inversion saturation preparation other undefined
[RF]
1 369.212 1 2 0 1500 100 0 0 0 0 e
"

My guess is Koma is pulling the center and setting that as the delay. If i delete the 1500 value in the .seq file then things line back up again

To check this i looked at the example epi_se.seq. It does not have a center time for the pulses
"
Format of RF events:
id amplitude mag_id phase_id time_shape_id delay freq phase
.. Hz .... .... .... us Hz rad
[RF]
1 329.152 1 2 0 100 0 0
2 1000 3 4 5 100 0 0
"
However if i remake the epi_se.seq file from the matlab script creatEPI.m I see a center time in the new .seq file. This leads me to believe there has been an update to pulseq than includes more RF timing information and that i am using this newer vewion of pulseq compared to whatever version originally made epi_se.seq
"
Format of RF events:
id ampl. mag_id phase_id time_shape_id center delay freqPPM phasePPM freq phase use
.. Hz .. .. .. us us ppm rad/MHz Hz rad ..
Field 'use' is the initial of: excitation refocusing inversion saturation preparation other undefined
[RF]
1 329.152 1 2 0 1500 100 0 0 0 0 u
2 1000 3 4 5 250 100 0 0 0 0 r
"

epi_se.seq old

epi_es.seq New

[cmwalker]

I checked PulSeq and they added the center for RF pulses with release v1.5.0 in Feb of 2025

[cncastillo]

We recently added support for Pulseq 1.5, could you update and try again? (] update KomaMRI)

Related:
#622 (comment)

[cmwalker]

I am still having issues. maybe i am not using the right version of Koma. looks like i am on 0.9.2 after "] update KomaMRI. Sadly i dont know how to check what the newest version is.

[pvillacorta]

Hi! Latest version of KomaMRIFiles is 0.9.9. Can you try to do ]update? That way, not only KomaMRI will update, but also its dependencies (including KomaMRIFiles).

[cncastillo]

For future reference, in the readme you can check the latest versions

[cmwalker]

that did the trick, thank you all! Koma has proved exceedingly useful for the course so far.