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 fischl@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 same (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 <fischl@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 triangles
?? ?su
rrounding the vertex? Best, Feng
发件人：Bruce Fischl <fischl@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. The
?? ?
?h.area files are for the white surface and the ?h.area.pial for the pial
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, what ?? ?ab
out
the surface area? Calculation based on pial or white matter? Or average
t
he
area of both of them.
Is the area of each vertex obtained by the average the area of triangle
s ?? ?> surrounding the vertex?
In addition, where can I find the definition of meancurv, gauscurv, fol
di
nd,
curvind? I do not find it in the fswiki.
Best, Feng
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