[Freesurfer] feeding data not processed with longitudinal pipeline into Linear Mixed Effects (LME) model

Hello Freesurfer experts,

I have two longitudinal datasets. In each dataset, some participants have only a single timepoint. For this reason, I aim to run the Linear Mixed Effects (LME) Model described at https://surfer.nmr.mgh.harvard.edu/fswiki/LinearMixedEffectsModels.

I understand that it is recommended that before running LME, I process my data using the longitudinal stream (e.g., https://surfer.nmr.mgh.harvard.edu/fswiki/LongitudinalProcessing). However:

1. in one dataset, some participants were scanned several years apart in early childhood, which caused the intra-subject registration to fail in the longitudinal processing stream

and

2. in the second dataset, editing of longitudinal timepoints was time prohibitive - several hours of edits were spent per brain at the cross-sectional level due to the use of an older sub-optimal pulse sequence. And, several more hours are required for the editing of each base or longitudinal timepoint.

Given each of these circumstances, is it feasible/appropriate to run LME using data that was not initially processed using the longitudinal processing stream within Freesurfer?

Thanks in advance! Lara

Lara Foland-Ross, Ph.D. Research Associate and Imaging Lab Manager Center for Interdisciplinary Brain Sciences Research Stanford University School of Medicine 401 Quarry Road, Room 1356 Stanford, CA 94305-5795