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Regression would be better than division.

Matt.

From: <freesurfer-bounces@nmr.mgh.harvard.edumailto:freesurfer-bounces@nmr.mgh.harvard.edu> on behalf of Damien MARIE <damien.marie@unige.chmailto:damien.marie@unige.ch> Reply-To: Freesurfer support list <freesurfer@nmr.mgh.harvard.edumailto:freesurfer@nmr.mgh.harvard.edu> Date: Monday, October 22, 2018 at 8:54 AM To: "freesurfer@nmr.mgh.harvard.edumailto:freesurfer@nmr.mgh.harvard.edu" <freesurfer@nmr.mgh.harvard.edumailto:freesurfer@nmr.mgh.harvard.edu> Subject: [Freesurfer] Myelinated cortical thickness ratio map

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Dear experts,

I am working with R1 maps that I project on the surface. The goal is to look at intra-cortical myelin.

I detect interesting effects between two groups. Now I would like to compute myelinated cortical thickness ratio maps, in order to control for the effect of cortical thickness variations occurring with gyrification.

Here is a paper where they describe a way to compute those myelinated cortical thickness ratio map with MIPAV and the MPI-CBS toolbox : https://www.ncbi.nlm.nih.gov/pubmed/29321232 « The proportional thickness of the myelinated part of the cortex in relation to its overall thickness (myelinated cortical thickness) was computed with a fuzzy classification technique combining information about radial and tangential fibers. «

1- Is it possible to do the same in FreeSurfer?

2- What about dividing my individual myelin maps by the individual cortical thickness maps? Is it possible to do that in FreeSurfer? SPM ImCalc would do the job in the volume but I don’t know how I could do that in FreeSurfer.

Any comments / other suggestions are welcome.

Thank you and best,

Damien

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