DT.nii and KT.nii

[Luoyu-Wang]

Hello everyone,

I have a couple of questions regarding the DT.nii and KT.nii that I hope you can help clarify.

1 Is the order of the components in DT.nii files consistent with those produced by FSL fitting?
2 For the KT.nii file, are the kurtosis coefficients ordered as Kxxxx, Kyyyy, Kzzzz, Kxxxy, etc.?
3 For multi-shell data, when calculating the DT.nii, is it the result of fitting from the DKI calculation, or is it derived from fitting DTI, such as by extracting data around b=1000? Could you please clarify this for my understanding?
I appreciate any insights or references you could provide on these topics. Thanks in advance for your help!

[TheJaeger]

Hi @Luoyu-Wang.

1. Tensor ordering is the same as MRTrix3, as referenced in their documentation here.
2. Likewise for KT.nii, same ordering referenced in documentation.
3. Muli-shell data processing is dynamic. If your data is DTI only with b-values up to 1500, then DT.nii is computed from DTI fitting. If, however, your dataset is DKI with b-values up to 3000, then DT.nii is computed from DKI fitting.

I hope this clarifies the matter.