Problems when working with both fMRI and dMRI data of HCP

Hello Fiona

Thanks again for your reply~I still have some confusion When performing the transformation between diffusion space and MNI space according to the files you provided.

In the PreFreeSurfer section of HCP Pipelines, The registration from T1w to MNI space generated two files, acpc2MNILinear.mat generated by flirt and ${OutputTransform} (i.e. acpc_dc2standard.nii.gz) generated by fnirt.

A s far as I know, the file acpc_dc2standard.nii.gz only contains non linear transformation, and the linear transformation file is not included in folder <subject>/MNINonLinear/xfms. I am not familiar with HCP Pipelines, and some understanding may be incorrect…

And I donnot understand ““acpc_dc”” , so could you please interpret the meaning of the term “acpc_dc” in the context for me? Thank you again~~~

Finally, I have another problem, could you please help me resolve it if you have free time? Thanks a lot!!!

Zack