Questions about metabolites quantification using MEGA-PRESS sequence editing GSH

Hi there,

I am trying to analyze some 3T Philip MEGA-PRES data with Osprey.

In the QuantifyResults, I found that most metabolites’ rawWaterScaled values (e.g., NAA, Cr, and Cho) were almost ten times higher than those reported in the literature. We have attached an example of the data.

屏幕截图 2024-06-22 104338 (1.9 MB)
OspreyJob.txt (827 Bytes)

Hi @Neuroimaging_ys,

Thanks for reaching out.

There are two potential sources for this issue:

I see you are using LCModel for the modeling instead of the Osprey native algorithm. For MEGA-PRESS, I have only implemented an LCModel wrapper for GABA-edited MRS so far. I am not sure if all the settings and function calls will work.

In addition, you are using your own basis set. How did you simulate this and would you be able to share it as well? Osprey uses a linear-combination model for the water fit, and if your water simulation in the basis set is wrong, you’ll get strange results.


Hi Helge,
Thanks for your reply. I have also used the Osprey native algorithm and the QuantifyResults were similar to the above attached. I suppose that there may be a problem with the calculation of the area under the water peak curve since what is unreasonable is the water-scaled metabolite values. I have shared the download link for the basis set file.

Hi @Neuroimaging_ys,

Osprey and LCModel have different ways to model the water data, if it is strange for Osprey and LCModel I’d suspect that there is a problem with the water reference scan.

I will take a look at it.