Myelin water fraction from GRASE image

1

Hi there!
I’ve recently met MRtrix and sort of fell in love with it, thus I am using it for a project.
I am currently working on this project whose purpose is the one of showing myelination progress across different subjects (differently aged) and I need to calculate MWF maps in order to realize where myelin actually is - unfortunately, huge amounts of theory and mysteries are all I can find online, thus I was wondering whether it would be possible to work it around by means of MRtrix!

Thanks in advance

2

I’m not sure exactly what you have in mind here. I’m sure there’s ways to do what you need with MRtrix, but depending on what it is exactly, you might need to create a new C++ command. But maybe there are things that can be done using existing commands – what do you need to do exactly? Are we talking non-negative least-squares fits to multi-echo T2 measurements…?

3

Thanks for your answer.
I’ve read different papers referring to Prasloski’s method involving NNL squares with multi-echo T2 measurements, indeed, but to me it not clear how to proceed in implementing it.

4

OK, well if you can write down the mathematical operation that needs to be performed per voxel, then we can start thinking about how to solve it. For instance, if it’s the same operation for each voxel, and of the form:

\textrm{min} \, \left| Ax-y \right|^2 \quad \textrm{such that} \quad Bx \geq 0

then there’s already a command for that. But if the operation is different, or the matrices A and/or B vary per voxel, then you’ll need to get your hands dirty…

5

Mmmh, I see it is quite straightforward!
I’ll try to use it and let you know - thank you very much!!