pretty much, although if you have saddle points the mean curvature can
disappear (since one direction has positive and the other negative
curvature)
On Sat, 27 May 2006, Fornito, Alexander wrote:
No, I don't need signed values necessarily.
So just to double-check then, higher mean curvature for averaged across a gyral
ROI label would mean the gyrus has a more steeply peaked appearance, whereas
high values for a sulcal label would, conversely, mean the sulcus resembles a
shraply bended valley?
Alex Fornito
M.Psych/PhD (clin. neuro.) candidate
Melbourne Neuropsychiatry Centre and Department of Psychology
National Neuroscience Facility
The University of Melbourne
Levels 2 & 3, Alan Gilbert Building
161 Barry St
Carlton South Vic 3053 Australia
Ph: +61 3 8344 1624
Fax: +61 3 9348 0469
email: [EMAIL PROTECTED]
-----Original Message-----
From: Bruce Fischl [mailto:[EMAIL PROTECTED]
Sent: Fri 5/26/2006 10:21 PM
To: Fornito, Alexander
Cc: freesurfer@nmr.mgh.harvard.edu
Subject: RE: [Freesurfer] ROI Curvature
p.s. sorry, the mean and Gaussian curvatures displayed in
mris_anatomical_stats are absolute value. I forgot this, sorry. The
integrate Gaussian curvature is actually a topological invariant, so
doesn't tell you much about the surface. Do you really need signed mean
curvaature averaged over a region? If so, you could specify -T curv, so
that the "thickness" is actually the curvature, and it will give you
the mean and std.
Bruce
On Fri, 26 May 2006, Fornito,
Alexander wrote:
Yup. That looks fine.
Alex Fornito
M.Psych/PhD (clin. neuro.) candidate
Melbourne Neuropsychiatry Centre and Department of Psychology
National Neuroscience Facility
The University of Melbourne
Levels 2 & 3, Alan Gilbert Building
161 Barry St
Carlton South Vic 3053 Australia
Ph: +61 3 8344 1624
Fax: +61 3 9348 0469
email: [EMAIL PROTECTED]
-----Original Message-----
From: Bruce Fischl [mailto:[EMAIL PROTECTED]
Sent: Fri 5/26/2006 9:44 PM
To: Fornito, Alexander
Cc: freesurfer@nmr.mgh.harvard.edu
Subject: RE: [Freesurfer] ROI Curvature
when you overlay the ?h.curv file on the inflated surface does it look
correct? Are there both red and green regions?
On Fri, 26 May 2006, Fornito,
Alexander wrote:
I mainly interested in the mean curvature.
This is output for a gyral ROI:
% 1001365: <wm vol> <surf area> <gray vol> <thick mean> <thick var> <integ rect. mean curv>
<integ rect. Gauss curv> <fold index> <intr curv ind>
647773 395 1297 3.145 0.780 0.151 0.027 4.123 0.572
This is for a sulcal ROI;
% 1001365: <wm vol> <surf area> <gray vol> <thick mean> <thick var> <integ rect. mean curv>
<integ rect. Gauss curv> <fold index> <intr curv ind>
647773 563 1693 2.992 0.567 0.121 0.068 48.616 4.783
Cheers,
Alex
Alex Fornito
M.Psych/PhD (clin. neuro.) candidate
Melbourne Neuropsychiatry Centre and Department of Psychology
National Neuroscience Facility
The University of Melbourne
Levels 2 & 3, Alan Gilbert Building
161 Barry St
Carlton South Vic 3053 Australia
Ph: +61 3 8344 1624
Fax: +61 3 9348 0469
email: [EMAIL PROTECTED]
-----Original Message-----
From: Bruce Fischl [mailto:[EMAIL PROTECTED]
Sent: Fri 5/26/2006 8:32 AM
To: Fornito, Alexander
Cc: freesurfer@nmr.mgh.harvard.edu
Subject: RE: [Freesurfer] ROI Curvature
which curvature values. Can you send the output?
On Fri, 26 May 2006, Fornito, Alexander wrote:
Sorry, got it wrong way around.
Either way, when I run mris_anatomical_stats on labels that I have created, I
tend to get positive values for mean curvature for labels of both gyral crowns
or sulcal fundi. Are the curvature values provided by mris_anatomical_stats
unsigned?
Alex Fornito
M.Psych/PhD (clin. neuro.) candidate
Melbourne Neuropsychiatry Centre and Department of Psychology
National Neuroscience Facility
The University of Melbourne
Levels 2 & 3, Alan Gilbert Building
161 Barry St
Carlton South Vic 3053 Australia
Ph: +61 3 8344 1624
Fax: +61 3 9348 0469
email: [EMAIL PROTECTED]
-----Original Message-----
From: Bruce Fischl [mailto:[EMAIL PROTECTED]
Sent: Thu 5/25/2006 9:09 PM
To: Fornito, Alexander
Cc: freesurfer@nmr.mgh.harvard.edu
Subject: Re: [Freesurfer] ROI Curvature
Hi Alex,
the gyri will should have negative mean curvature and the sulci positive.
You can overlay the ?h.curv map to check.
cheers,
Bruce
On Thu, 25 May 2006, Fornito,
Alexander wrote:
Hi,
I have some labels that I've drawn, which correspond to the gyral crown and
sulcal fundus of a given ROI. From what I understand, mean curvature provides
an index of the convexity/concavity of the region. I would therefore have
expected high positive values in the gyral ROI to represent a steeper peak in
the curvature of the crown, with values closed to zero representing a more
flattened gyrus. Converseley, I would have thought low negative values for the
fundus ROI would represent a steeper peak in the opposite direction, with
values closer to zero again reflecting flattened curvature.
In reality, the values I get for both sulcal and gyral labels (using
mris_anatomical_stats) tend to be both positive.
Hoping someone could tell me what I'm missing?
Thanks in advance,
Alex
Alex Fornito
M.Psych/PhD (clin. neuro.) candidate
Melbourne Neuropsychiatry Centre and Department of Psychology
National Neuroscience Facility
The University of Melbourne
Levels 2 & 3, Alan Gilbert Building
161 Barry St
Carlton South Vic 3053 Australia
Ph: +61 3 8344 1624
Fax: +61 3 9348 0469
email: [EMAIL PROTECTED]
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