We are conducting a longitudinal analysis and we have a subject who is missing the structural at baseline (it has fMRI data though). That subject returned for the 1st and the 2nd follow-up. Can we process the longitudinal pipeline the usual way and account for the missing baseline in the LME analysis? 

The other option would be to treat the 1st follow-up as baseline but we would like to be consistent with the fMRI analyses and keep the baseline time point.

Thanks!

Mihaela