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Hi Bruce,

Thanks for you answer.

I am trying to relate mean cortical thickness with cognitive impairment in a stroke population (cortical and sub cortical strokes).
Should I exclude patients with cortical lesions/ create a mask/ look only on contro-lesional hemisphere ?

Regards

Guillaume
From: freesurfer-bounces@nmr.mgh.harvard.edu <freesurfer-bounces@nmr.mgh.harvard.edu> on behalf of Bruce Fischl <fischl@nmr.mgh.harvard.edu>
Sent: Thursday, May 31, 2018 1:09 PM
To: Freesurfer support list
Subject: Re: [Freesurfer] Cortical thickness and cortical stroke
 
Hi Guillaume

I certainly wouldn't trust the thickness values anywhere near the lesion.
What exactly are you trying to compute?

cheers
Bruce
On Thu, 31 May 2018, Guillaume
Bellanger wrote:

>
>         External Email - Use Caution        
>
> Hi Freesurfers users,
>
> I am looking on cortical thickness after ischemic stroke, especially stroke with cortical
> involvment. Freesurfer is validated in this population, Li, Q. (2015).
>
> When I check the surfaces on Freeview, cortical infarcts are excluded (which is great because of the
> major anatomy distorsion) but the pial and white surfaces (in contact to the area excluded) are
> different from zero. It seems that Free-surfer still calculates the cortical thickness as an average
> measure of the surfaces in contact to the area excluded (which doesn't have any grey matter !). I
> send you a picture to illustrate my question.
>
> I am wondering: how does Freesurfer calculate the surfaces in contact to a cortical area excluded ?
> If the areas are excluded does it have any consequences on the GLM with QDEC ?
>
> Thanks a lot
>
> Guillaume
>
>
>