Gannet alpha correction of Glx

Analysis / Modeling Quantification / Calibration
1

Hi all,

I’m looking at some MEGA-PRESS data that has been analysed in Gannet (3.1 if I recall correctly).

I’m interested in GABA and Glx.

I understand that the alpha correction includes an alpha of .5, since this is the ratio of GABA+ in white matter to gray matter.

Gannet also gives an alpha corrected value for Glx - should I be using this? I can’t seem to find any literature that backs up the same assumption in Glx (or Glu or Gln) so my inclination is to avoid this correction for Glx, but wondered if I’m missing anything.

Thanks!

Molly

2

Hi Molly,

Here are some papers showing a 2:1 ratio of GM and WM Glu/Glx:

Note that in Gannet 3.1, the 0.5 alpha correction is fixed for any metabolite that is quantified. Since v3.2, the alpha correction is metabolite specific. v3.2 is available on GitHub here.

Mark

3

Oh perfect - thank you so much for this Mark, much appreciated!

Molly