Absolute Choline concentration

A quick question regarding Gannet:

Am I right in assuming that I could obtain absolute, tissue corrected choline concentration by performing the same calculations that is done for GABA but on Choline area under curve, that is to obtain a “ConcIU_CSFcorr” for choline?

Correct. You would just need to input the correct constants for the 3.2 ppm Cho peak in the formula. Have a look at the local function CalcIU in GannetFit.m (in the latest version) for reference.

Thank you!

So this would involve finding a reference for the constants then. I found Li et al (2013) JMID but if anyone knows of a more suitable reference I am open to suggestions.
However, I am afraid I cannot figure out what N_H_Metab represents.

Can you post a link to this reference? I can’t find it.
We have some T1 and T2 values for GM and WM in our lookup table in Osprey.

The 3.2 ppm signals from GPC and PCh both have nine protons (CH3)3.

Here is the full reference:
Li, Y. (2013). T1 and T2 Metabolite Relaxation Times in Normal Brain at 3T and 7T. Journal of Molecular Imaging & Dynamics, 02(02). https://doi.org/10.4172/2155-9937.S1-002

Thank you for the tip to look into Osprey!

I have to confess that I am clueless about the N_H_Metab variable, but I take it that your response about nine protons is in relation to that? :slight_smile:

The N_H_Metab constant is the number of hydrogen protons that give rise to the signal of interest. For the 3.2 ppm Cho peak, there are 9 protons. You need to account for this as the signal areas scale with the number of hydrogen protons.

Please see the Gannet documentation website for further details of all the variables.