I mean; if you devide the number of vertices by the area per aparc-parcellation, some parcellations have relatively more vertices per mm^2 as others. If you now would compute the average thickness in for example the lobe-parcellation, the thicknesses of some areas (the parcellations with relatively more vertices per mm^2) get a higher weight in the overal average. Is that true?
On Tue, May 28, 2013 at 8:58 PM, Douglas N Greve <greve@nmr.mgh.harvard.edu> wrote:
what do you mean? That the vertices are not uniform? mri_segstats just computes the mean over the parcellation without reference to non-uniformity.
doug
On 05/28/2013 02:15 PM, Martijn Steenwijk wrote:
Sorry, indeed, my reply was too quick. Seems to work, the results are similar to mri_anatomical_stats.
I'm not sure whether this is relevant; but the sampling seems to be not equally dense in the different regions. Does mri_segstats somehow cope with this?
Best,
Martijn
On Tue, May 28, 2013 at 8:03 PM, Martijn Steenwijk <martijnsteenwijk@gmail.com <mailto:martijnsteenwijk@gmail.com>> wrote:
Thanks Doug for your quick reply. But mri_segstats computes the
average value inside the cortical region in the volume, right?
That's not wat I want to have, I want to know the average value of
the data in the volume on the wm/gm surface (i sampled with
projfrac = 0).
Any thoughts?
On Tue, May 28, 2013 at 7:46 PM, Douglas N Greve
<greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu>> wrote:<mailto:Freesurfer@nmr.mgh.harvard.edu>
I would use mri_segstats and specify the --annot option
doug
On 05/28/2013 01:28 PM, Martijn Steenwijk wrote:
> Dear all,
>
> I've created a custom '.mgh' file containing values on the
cortical
> surface using mri_vol2surf. I would like to compute some
statistics on
> this surface in the aparc-areas computed by freesurfer. Can
I then
> just use mri_anatomical_stats with option -t specifying the
custom
> mgh file as 'thickness' input? Or does mri_anatomical_stats
something
> more complex than just averaging the values inside each region?
>
> Best,
> Martijn
>
>
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