For the longitudinal pipeline, the website/ recon-all -help suggested that I calculate the different on the results from the longitudinal command (e.g. tp2.long.longbase - tp1.long.longbase). Let say, my timepoints were named 1001_Baseline.long.longbase and 1001_Followup.long.longbase; is there a command i can use to preform this? 

Second question, i want to extract the output of the longitudinal pipeline using asegstats2table and aparcstats2table commands. what flag/s should i include in  the original command to perform this? 

Thanks. 

Paul