Yes indeed there were 3 subjects at the bottom-left of the plot. 

To account for PV, I eroded the boundaries using -seg-erode 1 during the mri_segstats stage, and this resulted in a few subjects with no data for the WM entorhinal region (although these were saved as "0" in the .stats file). Do people generally do this for DTI studies?

All good now. 

Many thanks again, Kirstie.

Best Wishes,

Elijah