From greve@nmr.mgh.harvard.edu Tue Oct 14 11:39:11 2014
From: Douglas N Greve <greve@nmr.mgh.harvard.edu>
To: freesurfer@nmr.mgh.harvard.edu
Subject:
 Re: [Freesurfer] cortical surface area measurement and vertex-wise analysis
Date: Tue, 14 Oct 2014 11:39:10 -0400
Message-ID: <543D439E.40801@nmr.mgh.harvard.edu>
In-Reply-To:
 <CA+BXJQLWSb32YVvn6pQFHyHWaxut-sQ6Lp40MLXL7LRUz8DaZQ@mail.gmail.com>
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If you are using --qcache, then there is nothing wrong specifically with=20
the qdec implementation

On 10/13/2014 03:11 PM, Emma Thompson wrote:
> Hi Anderson,
> Thank you for your paper. I guess I am confused. I have analyzed my=20
> structural data with qdec, specifically looking at a measure of=20
> cortical thickness and volume. I'm considering looking at surface area=20
> as well but was told it wasn't a very good measure using qdec, I have=20
> no other information really. Could you speak to whether or not this=20
> measure is valid in so far as one runs it using qdec?
>
> Also, in your opinion, would it be redundant to look at surface area=20
> in addition to measures of cortical thickness and cortical volume?
>
> Thanks for your help and apologizes for my silly questions.
>
> On Sun, Oct 12, 2014 at 3:00 PM, Anderson M. Winkler=20
> <winkler(a)fmrib.ox.ac.uk <mailto:winkler(a)fmrib.ox.ac.uk>> wrote:
>
>     Hi Donna,
>
>     In that same paper we also comment on the differences between
>     expansion/contraction and absolute areal measurements assessed at
>     each face of the surface (i.e., facewise), which can, after
>     interpolation, be converted to vertexwise to facilitate analysis
>     using current tools (e.g., mri_glmfit or qdec), without loss of
>     areal quantities.
>
>     All the best,
>
>     Anderson
>
>
>     On 11 October 2014 04:05, Donna Dierker <donna(a)brainvis.wustl.edu
>     <mailto:donna(a)brainvis.wustl.edu>> wrote:
>
>         Hi Emma,
>
>         I might not be the only one who is unsure what you mean by a
>         vertex-wise cortical surface area measure. Do you mean
>         something like what is illustrated in figures 2 and 3 here:
>
>         http://www.pnas.org/content/107/29/13135.figures-only
>
>         =E2=80=A6 which is similar, but not identical to the local
>         gyrification index?
>
>         If so, would you use this measure on surfaces before or after
>         registration to a target atlas?
>
>         Donna
>
>
>         On Oct 10, 2014, at 4:19 PM, Emma Thompson
>         <voneconomos(a)gmail.com <mailto:voneconomos(a)gmail.com>> wrote:
>
>         > Dear Freesurfers,
>         > I recently heard that there are several disadvantages to
>         using a measure of cortical surface area in Freesurfer,
>         specifically due to conducting a vertex-wise analysis. Can
>         someone help me understand why a measure of surface area using
>         this approach might be flawed? Thanks!
>
>
>
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--=20
Douglas N. Greve, Ph.D.
MGH-NMR Center
greve(a)nmr.mgh.harvard.edu
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