[Freesurfer] Consistency between volumes in fsaverage and subject data?

Hi Freesurfer users,

I am analysing some volumetric data and have noticed that the volumes I extract from my participants are very different from the volumes of my templates in fsaverage space. I for instance have two ROIs that stand out as big (about 6-8 times larger that the other ROIS) in fsaverage space, but come out as almost indistinguishable from the other ROIs in my data. When I sort my ROIs according to size there seems to be no consistency between the size in fsaverage space and my subjects, and the correlation between the volume in fsaverage and my subjects is about .05 - 0.1.

I am new to freesurfer, and would intuitively expect greater consistency between the ROIs in fsaverage and the subjects. Has anyone else had similar experiences, and is this lack of consistency between volumes in fsaverage space and participant data perfectly normal?

Thanks,

Sarah