Hi,

My understanding of etiv is that it is derived from the registration of a brain to atlas space and not actually derived from the freesurfer segmentation. I have a set of patients imaged at 2 time points that all have different etiv values between the first and second scan that are statistically significant. As there was no change in their skulls between scans, I am having difficulty understanding how this is possible. Can anyone suggest what I may be doing wrong?

Best wishes,

Salil