Many thanks for the information, Doug! I will give it a go. 

Actually, I would like to carry out the following analyses: 

Get regional estimates of perfusion within a region of interest as defined by a significant cluster after mri_glmfit-sim. as well as other cortical regions that are connected to that cluster in terms of WM paths. Is it possible to do that in Freesurfer environment?

How can I do PVC for perfusion in  ROIs? Will the -pv ppvol flag be crucial during the mri_segstats stage? 

Thanks again for help.

Best Wishes,

Elijah