You can get that kind of information a few ways. There are two kinds of labels associated with ROIs - labels from a labeltable, labels from an atlas_point_list. Most atlases have both kinds. ROIs drawn with the Draw Dataset plugin will have a labeltable.
1. 3dinfo -atlas_points atlasdset.nii.gz
2. 3dinfo -labeltable labeldset.nii.gz
3. whereami -atlas "atlasname" -show_atlas_code (if you leave out the "-atlas" option, all atlas regions are shown with their index codes)
4. 3dROIstats automatically shows labels of regions included in the column headings
