> Could you please clarify what you mean when asking how the results look to me?
Do you get the results you expected to see? Do the results survive the harsh penalty of multiple testing adjustment?
> I have anatomically defined 4 ROIs
With 4 ROIs, it would be too few regions to effectively perform Bayesian multilevel modeling.
> whether there is either any "small volume correction" available within the 3dISC framework
Are these 4 ROIs contiguous? If so, you could create a mask and apply the routine multiple testing adjustment with the mask.
Gang