hi, would it be acceptable in a paper using the HERCULES sequence to draw from the alpha-corrected water scaled table in Osprey for GABA+, Glu, Gln, Glx, and the tissue corrected water scaled table for other metabolites? Are there examples in the literature that mix alpha correction with just tissue correction when reporting or is this a bad idea? I understand that the type of correction can change results
Glu (and by extension Glx, because it’s largely Glu) is roughly twice as concentrated in GM than WM from my own literature search, so I personally would apply a 2:1 GM:WM alpha correction to those concentration estimates.
I can’t think of an example where the two tissue-correction approaches have both been used. Ultimately, the most important thing is to state clearly how you corrected your values and if the procedure differed between metabolites (and why).
Note also that an alpha-correction as implemented by Harris et al. is more like a normalization: That is, “what would all participants’ Glu measurements be if their voxels were all 100% WM.” This is important to understand if comparing to other studies’ results.