 
Dear Bruce,

Once again many thanks for helping.I am not using tracula. I used the dt_recon and I have done the registration for my FA data on the cvs space using the mri_cvs_register.  I used the GLM group analysis method after I concatenate FA from individuals into one file and used


mri_glmfit-sim \
  --glmdir Group_Analysis.glmdir \
  --grf 2 neg \
  --cwpvalthresh .025 \
  --overwrite

to cache the significant clusters after multiple comparisons so I have the uncorrected and corrected significant map but I don't know how I can see if  my FA is
 increasing or decreasing in controls group
 versus patients group. 


Please advise me.

Thank you.
Antonella