- I would recommend using the same TR for both classes of scans (short-TE and MEGA-PRESS). 1.5 s is very short (heavy T1 weighting)… does your protocol time allow for all scans to have 3 s TR? 2 s is a compromise.
- Set water suppression bandwidth to be the same for both classes of scans.
- Set vector size and bandwidth to be the same for both classes of scans. 2048 pts / 2000 Hz seems as good a combination as any.
- PRESS delta frequency is commonly set to -2.3 ppm to localize glutamate as displayed. Honestly, I think this is perfectly fine.
- Use the same shim settings for both classes of scans. What options do you have available?
There are some threads discussing Siemens shimming options ( How to measure metabolites in occipito-temporal cortex? - Data Acquisition - MRSHub Forum).
I don’t have a PDF printout ready at hand (we’re a mostly-Philips site) but I’d feel pretty comfortable with your protocol now.