Our lab have managed to generate ROIs in T1 images using Freesurfer, which led to .label files. We succesfully measured the cortical thickness in these ROIs for each subject in Freesurfer. Now we are aiming to track white matter fibers from these ROIs in a tractography software Trackvis. However, .lable files seem not be readable in Trackvis. Thus, we are wondering if .label files can be tranferred to .nii files easily in Freesurfer so that we can use the converted .nii ROI files to track fibers in Trackvis. Another related question is how can we coregister the ROIs drawn in T1 images with DTI images and make sure that those ROIs converted from T1 images are the still in the same regions in the DTI images?