Is there a way to extract the significant clusters as masks from significant group comparisons using qdec?

All I can seem to find is  mri_glmfit-sim which doesn't quite replicate the QDEC FDR 0.05 output and doesn't seem to make anything that I could extract as a label, or hand drawing an ROI. 

I am working with a longitudinal model of cortical thickness, and would like to extract the average thickness of each significant cluster to understand the change in thickness. 

Thank you. 

Kate Damme