As part of my project, I would need to have subthalamic nucleus as one of my ROIs in which this is not available by Freesurfer. I found a probabilistic subthalamic nucleus atlas in FSL atlases (in MNI152 space) and thought I would convert this to fsaverage space. I have attempted:

mri_label2vol —reg $FREESURFER_HOME/average/mni152.register.dat —seg STN-maxprob-thr25-0.5mm.nii.gz —temp $FREESURFER_HOME/subjects/fsaverage/mri/orig.mgz —o STN_mni152_in_mni305.nii.gz

But the location was much more dorsal than original, 

1) I was wondering if there are alternative methods I should try and what could have been the problem? 

At the end, I hope to obtain individual subject’s subthalamic nucleus volume, 

2) I was wondering how to convert volume in fsaverage space to labels in fsaverage space so that I can convert the labels to native space?