Longitudinal Surface Based Morphometry Approach

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Hi all,

I have processed some data with MindBoggle (latest version 1.3.8, no errors reported) with the intention of running a whole-brain longitudinal surface based morphometry analysis.

The basic question I am trying to answer is where in the brain does change in thickness relate to change in a cognitive measure (both cognitive measures and anatomical MRI were acquired before and after an intervention). So, I am trying to compute a longitudinal thickness difference vertex-by-vertex (as opposed to looking at thickness averages within FreeSurfer/ANTs anatomical labels).

A problem is that I cannot figure out how to correspond vertices values from one session to another. The tables in $MINDBOGGLE_SUBJECT_OUTDIR/ses-pre/table/left_cortical_surface/vertices.csv and $MINDBOGGLE_SUBJECT_OUTDIR/ses-post/table/left_cortical_surface/vertices.csv have different number of rows, so it is probably not a one-to-one mapping.

How should I best proceed?

Thanks,
Steven

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Hello, Steven. It’s been a while since I’ve worked with FreeSurfer meshes, but each reconstruction from a volume will result in a different number of vertices. To get a 1-to-1 mapping, I believe you would need to register one to the other or to coregister them both to a template surface mesh (SurfaceRegAndTemplates - Free Surfer Wiki). The latter would make more sense if comparing longitudinal meshes, since you want to compare vertex values across time. Also see LongitudinalProcessing - Free Surfer Wiki.

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Got it, thanks @binarybottle!