Hi all,

Recently I tried out longitudinal processing on my 1st time point subjects ( directly generated by recon-all, no post processing or manual editing involved) . Then I ran asegstat2table for both 1st and 2nd time point subjects to compare cortical WM and cortical cortex volumes. From what I observed , there was possibly  a bias_shift in WM between those time points as most of the differences ( WM at tp2 -WM at tp1 ) were positive , I was expecting the mean difference would be close to 0 . It would be great if anyone could share her/his insights about this .Is it normal and what might cause this behavior ?

Thanks alot