We are running a longitudinal study with 4 time points. The first two time points were processed and edited with the 5.3 version of Freesurfer and the other two time points with FS6. I assume we have to re-run the first two time points with the new versión, but is there a way to preserve the editings?

In the same line, on a transversal study, would it be a lot of bias if most of the subjects of one group are processed with version 5.3 and most of the subjects of the other group with FS6?

Thanks a lot for your time