Calculate FA and RD

I am working on working memory bundle extracted from a combination of dIRM data and fMRI data. I want now to calculate the Fractional Anisotropy and Radial Diffusivity.
Any guidance is appreciated.

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The commands you’ll need are dwi2tensor, to fit a diffusion tensor to the signal in each voxel, and tensor2metric, to calculate FA and MD from the estimated tensor maps.

Have a look at the documentation here and here.

When I tried with dwi2tensor and I used a binary mask to perform computation there’s an error message after running:
dimension mismatch between “dwi.nii” and “mask.nii” between axes 0 and 2 (145,174,145,108 vs. 91,109,91)
mrinfo dwi.nii Dimensions: 145 x 174 x 145 x 108
mrinfo mask.nii Dimensions: 91x 109x 91

Voxel-wise operations in MRtrix require the mask to have the same image dimensions, voxel size, and transformation matrix as the dMRI image. If this is not the case, you either need to interpolate the mask in dMRI space (mrtransform with the -template option) or compute a new mask with dwi2mask.

@dchristiaens Thank you so much for your help !!
I want to compare each map generated by the others.
What can I do?