Dear Gabriel,
the lh.gyrification* files can be either used for a vertex-vise analysis or for focussing on ROIs. The latter can be achieved by using the "Analyze ROIs" tool or by Extract ROI Data -> Estimate Mean Values inside ROI for external Analysis. The "Analyze ROIs" function has the advantage that you can use your existing GLM model form the vertex-vise analysis which also includes all nuisance parameters.
If you analyze data from MS patients and you have also acquired FLAIR or T2 data the best way to analyze these data is to use the LST toolbox first to fill the lesions in the T1 image and subsequently use the filled T1 data with CAT12.
Please also note, that gyrification is a sensitive method for finding neurodevelopmental effects because cortical folding remains quite stable after the first years after birth. If you find differences in folding or gyrification in adults this would point to an early impact probably due to neurodevelopmental effects. Thus, it's not thought as general method for any kind of data and you have to have a clear hypothesis about your sample.
Best,
Christian
On Tue, 19 Dec 2017 16:19:46 +0100, gabriele pasqua <[log in to unmask]> wrote:
>Hi,
>I used the Preprocessing step "Segment Data" in order to compute the
>cortical thickness of patients with Sclerosis Multiple.
>I computed the gyrification idex too with the Surface Tool "Extract
>Additional Surface Parameters", I obtained the files "lh.gyrification.s..."
>and "rh.gyrification.s..."
>I can see the colour map of the brain with gyrification index, but how can
>I extract the numeric values (GI) of gyrification? Can I obtain the mean
>value of the whole brain? and the one of specific ROIs?
>
>thank you in advance
>
>Gabriel
>
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