DW gradient image header

Dear community:
I am having issues doing the preprocessing for structural connectome. I have done eddy with openmp version of FSL. But the issue comes when I want to do
dwibiascorrect ants sub-02_den_preproc.mif sub-02_den_preproc_unbiased.mif -bias bias.mif
I don’t have “bias.mif”. All I did was converting eddy output file into mif with mrconvert.

I have this error.
dwibiascorrect: [ERROR] No valid DW gradient scheme provided or present in image header

This will most likely be the problem. How exactly did you perform this step? If you didn’t include the bvecs/bvals at conversion time, DW gradient scheme won’t be available in the image header of the sub-02_den_preproc.mif image, which this command expects to find. You can trivially check for this by running:

mrinfo sub-02_den_preproc.mif

and check if there is a DW scheme entry in the output.

If you need to convert DWI data from NIfTI to mif, you should pretty much always make sure the corresponding bvecs/bvals are also included in there, like this:

mrconvert dwi.nii -fslgrad bvecs bvals dwi.mif

oh thank you very much. I didn’t includ th bvec bvals so that is the issue.