Hi ! 
I have 14 VOI and 50 subjects. I want to extract mean and SD of each VOI on each subject. 
With the Draw: descriptives function I have these information 3 times:

VOI nvox(cc)=min/mean/max SD
VOI <>0  nvox(cc)=min/mean/max SD
VOI >0 nvox(cc)=min/mean/max SD
 
Would you please explain what is the difference ?

and I would like to batch this but I didn't find any guide... 
Thank you
Isabelle

This reports the number of voxels (nvox) and cubic centimeters (cc). you are told the darkest (minimum), average (mean), maximum (max) and standard deviation (SD) for the voxel brightnesses under the VOI. 

You are provided with three forms of this information:
 1.) For all voxels under the VOI
 2.) For all non-zero voxels ("VOI <> 0")
 3.) For all voxels brighter than zero ("VOI > 0")
The latter two options are useful for masked images.

-c