I assume that you have more than two subjects as input.
> It seems that the only output is a 3D dataset and I'm not sure how to interpret the results in the GUI.
There should have more than one sub-brick in the output. The one with the label 'Subj' is the ICC you're looking for.
> Also, is there a way to add an option to quantify values in a text file or something?
This is a whole-brain voxel-wise ICC analysis. I'm not so sure what you're asking. If you want to the ICC for a particular list of ROIs, you can extract them from the whole brain analysis results.
Gang