[Freesurfer] Question concerning Fractional Anisotropy

Hello,

I am trying to run the dt_recon with the fractional anisotropy to do a project with white matter.

I am running into a problem actually getting the command to work.

I am trying to follow the example online

dt_recon --i 6-1025.dcm --s M87102113 --o dti dt_recon --i f.nii --b f.bvals f.bvecs --s M87102113 --o dti

But I am not sure where/what I am supposed to put after the -i.

The other stuff I am pretty sure I know, --s = the subject folder --o = the folder I want the output to go in

Can you fill me in on what I'm missing, I looked in the subjects output files and could not find anything that ended with .dcm.

Thank you,

Brian Weisinger