Hi Prof. Greve, Thanks for your reply. Sorry, perhaps I have made some mistake in my data analysis. I just want to show tractography results of basal ganglia in surface space using FSL. Could transform fit_paths.nii.gz to surface be a brief way? In order to do mdi_vol2surf (transform volume ROIs in T1 space to surface) I should have register.dat. Is that a correct way to get it using "bbregister --s SubID --mov T1.nii --init-fsl --reg register.dat " Sincerely, Jinnan