Hi Feng
thickness has a biological meaning as a point measure, but area does not.
The area of any given triangle doesn't carry any biologically relevant
information that I can think of, which is why we don't quantify the
statistics of the area of individual triangles
cheers
Bruce
On Wed, 7 Oct 2015, chenhf_uestc wrote:
I thought that we calculate the Surface area, MeanCurv, GausCurv, FoldInd
and CurvInd in each vertex, and thus we can obtain the whole map on the
surface.
Subsequently, using the predefined atlas, we can further obtain the mean and
std value in each brain region (because each vertex has a value). It looks
like you do not calculate surface area and other measures in the
aforementioned way, right?
From your words, it may be that the surface area is the summation of each
vertex's area in each region, right? In contrast, for thickness, you compute
the mean thickness across all the vertics. And of coz, I can compute the
total thickness in each region like the area (summation of each vertex's
thickness in each region), right?
Best,
Feng
____________________________________________________________________________
发件人：Bruce Fischl <fis...@nmr.mgh.harvard.edu>
发送时间：2015-10-07 22:32
主题：Re: [Freesurfer] Query about the calculation of surface area
收件人："Freesurfer support list"<freesurfer@nmr.mgh.harvard.edu>
抄送：
Hi Feng
they are slightly different measures so which one you use really depends
on your biological hypothesis.
For thickness there are multiple measures within each ROI but only one area
(that of the whole ROI), so mean and std doesn't make sense.
cheers
Bruce
On Wed, 7 Oct 2015, chenhf_uestc wrote:
> Thanks a lot, Bruce
>
> If I want to compare the surface area between the patients and healthy
> control groups, which area file should I use? The area or the area.pial?
?? ?Or
> I should compare both of them? If I should use both, is there any
> possibility that I would obtain different results from area and area.pial
? I
> mean, in this case, a brain region has significantly different area but s
ame
> (not significant) area.pial. How can I explain them in my research paper?
>
> BTW, just out of curiosity, in the stats file such as lh.aparc.stats, why
> just thickness has the mean and std value, but other measures do not have
> the std value?
> SurfArea GrayVol ThickAvg ThickStd MeanCurv GausCurv FoldInd CurvInd
>
> Best,
> Feng
>
> _________________________________________________________________________
___
> 发件人：Bruce Fischl <fis...@nmr.mgh.harvard.edu>
> 发送时间：2015-10-06 20:45
> 主题：Re: [Freesurfer] Query about the calculation of surface area
> 收件人："Freesurfer support list"<freesurfer@nmr.mgh.harvard.edu>
> 抄送：
>
> yes, that is correct
> Bruce
>
>
> On Tue, 6 Oct 2015, chenhf_uestc wrote:
>
> > Thanks, Bruce So, in the stats folder of each subject, the
> > lh.aparc.a2009s.stats file provides surfarea of each region. This value
?? ?> is the area for the white surface, right?
> > Is the area of each vertex obtained by the average the area of triangle
s
?? ?su
> > rrounding the vertex? Best, Feng
> >
> > _______________________________________________________________________
__
> ___
> > 发件人：Bruce Fischl <fis...@nmr.mgh.harvard.edu>
> > 发送时间：2015-10-06 20:25
> > 主题：Re: [Freesurfer] Query about the calculation of surface area
> > 收件人："Freesurfer support list"<freesurfer@nmr.mgh.harvard.edu>
> > 抄送：
> >
> > Hi Feng
> >
> > we compute the surface area of each surface and store it separately. Th
e
?? ?
> > ?h.area files are for the white surface and the ?h.area.pial for the pi
al
>
> >
> > cheers
> > Bruce
> > On
> > Tue, 6 Oct 2015, chenhf_uestc wrote:
> >
> > > Dear Freesurfer experts,
> > >
> > > I have a question about the calculation of surface area. The cortical
?? ?> > thickness is the distance between the pial and white matter. But, w
hat
?? ?ab
> > out
> > > the surface area? Calculation based on pial or white matter? Or avera
ge
> t
> > he
> > > area of both of them.
> > >
> > > Is the area of each vertex obtained by the average the area of triang
le
> s
> ?? ?> surrounding the vertex?
> > > In addition, where can I find the definition of meancurv, gauscurv, f
ol
> di
> > nd,
> > > curvind? I do not find it in the fswiki.
> > >
> > > Best,
> > > Feng
> > >
> > >
> > >
> > _______________________________________________
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> >
> >
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> > s
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?? ?e-
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