[Freesurfer] mri_cnr

hi fellas,

i am trying to run mri_cnr command in freesurfer to compute and see CNR for gray/white/csf.... the command gives following info as help:

-bash-3.2$ mri_cnr usage: mri_cnr [options] <surf directory> <vol 1> <vol 2> ... -s <slope fname> <dist in> <dist out> <step in> <step out>

i understand that 'surf directory'= subjects 'surf' folder ; but i am not able to figure out what it means by vol1, vol2 and slope fname......it doesnt show any error but just doesnt do anything even if i mention the surf directory to this command.....

i checked on freesurfer mail archive, but no info since 2009 about any update on this command.....

may someone please give an info if anyone ever used this command

thanks kk