Add support for pulseq sequences

[chaithyagr]

Currently the only missing component is to have kspace trajectories from mrinufft to run on scanner. For this it would help a lot to have a pulseq sequences generation as an extras module with dependency on pypulseq

This is more of discussion thread for now before we work on it

[paquiteau]

If we could get some insights from people more knowledgeable about (py)pulseq that would be great as well !

[Daval-G]

I think pypulseq is not designed to easily generate gradients on one side and plug them into any sequence, because of the way the blocks & timings are systematically defined relatively to other blocks. Both gradients & pulse sequence have to be defined together, or it would take an heavy layer of in-depth object manipulation to go around that. Maybe I am wrong, and I would prefer it

[Daval-G]

But we could still propose some basic GRE sequences, given the user provides a bunch of system infos. Is it what you meant @chaithyagr ?

[chaithyagr]

Well to begin with yes, GRE and inversion. I do have basic scripts. I can make them to functions.
I expect it to be like you define the scanner config, the acquisition config and give the trajectory, it gives a seq file for you.

[paquiteau]

For scanner config and acquisition, have a look at how I did in SNAKE (if its missing something, let's add it to SNAKE as well btw).

Otherwise, how hard would it be to have an arbitrary gradient readout in pulseq (just as you did for siemens) ?

[chaithyagr]

Really not that hard, it's all just a short function. I will try to keep it modular... Done fun coding back to Paris i guess xD

[chaithyagr]

https://github.com/imr-framework/pypulseq/blob/master/examples%2Fscripts%2Fwrite_radial_gre.py

Here's a simple radial gre example. We need to make ours modular though..