nifti_tool -cbl -prefix fa.nii -infiles sample-dwi.nii'[18]' 
3dSkullStrip -input ./sample-anat.nii -prefix sample-anat-brain.nii
3dAllineate -base sample-anat-brain.nii -source fa.nii -prefix fa-al.nii
3dQwarp -base sample-anat-brain.nii -source fa-al.nii -prefix fa2anat.nii