Processing for DW-MRS

Study & Experiment Design DW-MRS
1

This sub-section can be use to:

  • find material to process your DW-MRS data (link to packages, useful functions depending on packages etc).
  • propose new material to process DW-MRS data.
  • discuss processing strategies.

Packages:

FID-A

FSL-MRS

Osprey

jMRUI

The LCModel is now free and can be downloaded from the LCModel webpage.

2

Updated Table 3 from the dMRS consensus paper can be found here:

It details what processing & fitting steps are included in the different packages.

3

Cross-terms
In the attached b_val_calc.zip file (courtesy of Chloé Najac), you’ll find a guide to calculate cross-terms in a sLASER sequence. It contains 3 files:

  • “Calculating the b.pdf” : a readme to understand what are the Sequence_Gradients.mat and calc_b_sLASER.m files, and how to use them
  • Sequence_Gradients.mat: example of sequence chronogram
  • calc_b_sLASER.m: a Matlab script to calculate the b_matrix and b_iso.
    b_val_calc.zip (293.6 KB)
4

Hi!

Thank you for sharing processing code for dMRS (and other fantastic resources)! I have a question about calc_b_sLASER function.

In the code I see a section for shifting the RF pulses (screenshot below).

image

Can you explain the reason why we would want to shift the pulses?

Thank you so much for your help in advance!

All the best,
Hande Halilibrahimoglu

5

Hi Hande,

Quick reply - I didn’t write the function myself (I think this example was given by Chloé Najac). But usually you want to shift the RF pulse to centre your excitation and refocusing in the middle of your spectra, so that you minimise the chemical shift displacement error (and you acquire you metabolites where you think you acquire them when you place your voxel).

I hope you are doing well !

Best,

Clémence

6

Hi Clémence,

Hope you’re doing good as well! Thank you for the explanation.

Have lovely day!
Best,
Hande