I’m new to MRS and trying to jump in the deep-end . We’re using a hybrid GE PET-MR and I have acquired some p files using the GE-WIP MEGA-PRESS sequence TE=110 and I wonder if anyone already has some basis files prepared for this that they would be willing to share? It seems likely we may have to simulate these.

Another question - does anyone know if the GE WIP sequence stores alternating rows of ON/OFF data, which seems to be assumed in Gannet?

Thanks in advance, I appreciate all the info here. As a rookie I would be lost without this resource!

  • Chris

Hi Chris,
I’m also new to MEGA-PRESS, but perhaps we can help each other.
I work on a 3T GE Discovery 750, so I also use P-files.
Have you tried MRSCloud for Basis Sets?
Sign up and log in. Then click on MRSCloud
Pick your metabolites, sequence (PRESS), vendor (GE), click MEGA under ‘editing’, then pick your ppms and duration

Let me know how it goes!

I am currently trying to use fsl-mrs to process these


Alex W.

Hi @chollen,

Our site also has a GE and I’m actively acquiring MEGA-PRESS data (amongst other acquisition types).

@chollen: Yes, if you are using the GE WIP—and not someone else’s sequence—the data are acquired interleaved. But that assumes which version of the WIP you’re using and your acquisition parameters. If Gannet is not working for you, either reach out to me directly ( or you can try a different software package.

As @weberam2 said, MRSCloud is a great option for creating a basis set. Although, this depends on what your target metabolite(s) you’re editing and your pulse sequence timings.


Hi @chollen,

We’ve had good outcomes using Gannet for MEGA-edited GSH on the MR 750 (some years ago now); the data are acquired and loaded interleaved, one thing you may need to be careful of is the order of the on/off pulses (ie, CV20, CV21)

If you do choose to simulate your own basis set, be aware that some of the timing parameters (eg, TE1/tau1) will vary depending on your chosen TE and RF pulse shape (CV19), as mentioned by @mmikkel. The default parameters assumed by certain tools will not necessarily be correct in your context.