7T sLASER Basis set

[Yushan]

@wclarke Hi William,

Here is the section of the code where metabolites are selected. I would like to ask if I want to simulate another chemical substance, such as acetate, and I know its ppm and J-coupling constants, where should I add this information?

[run4life_lq]

hello, Dear Clarke,

I have carefully read the code, but I still have some questions that I hope you can help me.

I would be grateful if you could provide more insights regarding the code (sequences/eja_svs_slaser/generate.py · master · William Clarke / WIN MRS Basis Sets · GitLab):

1. How should I interpret line 78 in the image below? What does the value 500 represent?
   
   

Thank you very much for your time and help.

Best regards,

Allan

[run4life_lq]

2. In the following code snippet, line 85 has a default parameter of 200. Is it necessary to modify this parameter based on specific situations? Do you have any suggestions for adjusting this parameter?

[run4life_lq]

3. In the next code segment, line 88 has a default parameter of 100. Should this parameter be modified according to circumstances? Do you have any recommendations for adjusting it?

[wclarke]

Hi @Yushan, You can pass custom spin systems to the fsl_mrs_sim using the -s flag, poining to a json file with the format matched to .e.g. spinSystems.json · master · William Clarke / denMatSim · GitLab

I.e. For a metabolite with two uncoupled spins at 0 and 1 ppm

"my_metabolite":{
        "j": [[0, 0], [0, 0]],
        "shifts": [0.0, 1.0],
        "name": "my_metabolite",
        "scaleFactor": 1}

[wclarke]

Hi @run4life_lq This line calculates the γB1 (measured in hertz) that the excitation pulse requires to perform a 90 degree excitation. This is referenced to a 1 ms pulse trying to achieve a 180 degree flip, which would require a 500 Hz γB1. So for a 90 degree 1ms pulse the outcome would be 250 Hz, but this is also scaled by the pulse amplitude integral (amp_int_rel).

[wclarke]

200 points should be reasonable for this sequence.

[wclarke]

This is just a constant term used for the shaping of the pulses, it shouldn’t be modified. There is some older adiabatic pulse literature on its optimisation.