yes, I believe so
On Mon, 3 Oct 2016, Hanbyul Cho wrote:
Dear Bruce Fischl
?h.white.H, ?h.curv, and H Mean reflected the vector fields with 'sign(+ or
-)', and MeanCurv reflected the integral of the 'absolute' value of mean
curvature. Am I understanding this correctly?
Best Wishes,
Han
On Mon, Oct 3, 2016 at 7:49 AM, Bruce Fischl <fis...@nmr.mgh.harvard.edu>
wrote:
Hi Han
I'm not sure I understand you question. The sign of the
curvature depends on the arbirary convention you choose for the
normal vector field over the surface. We pick and outwards
pointing normal, which means that gyral regions in general have
negative curvature (since they lie 'below' the tangent plane in
terms of their dot product with the normal) and sulcal ones are
positive. AFAIK both the ?h.white.H and ?h.curv curvatures obey
this convention, although the smoothing applied to the ?h.curv
will mean that some places they will have different sign. If you
plot them both you will see that they are pretty highly
correlated though.
Does that answer your question? If not, can you clarify?
cheers
Bruce
On Sun, 2 Oct 2016, Hanbyul Cho wrote:
Dear FreeSurfer Team,
I apologize for the repetitive questions.
I made 2 labels which included bilateral paracentral
lobule and sulcus
regions.
Then I extract the values:
- MeanCurv
After mris_anatomical_stats processing, I
extracted the MeanCurv by the
command,
'aparcstats2table --hemi ?h --parc <label> --meas
meancurv --subjects
<subjects list> --tablefile <output.txt>'
- ?h.Curv
After mris_anatomical_stats processing with
the option '-t lh.curv', I
extracted the curvature value by the command,
'aparcstats2table --hemi ?h --parc <label> --meas
thickness--subjects
<subjects list> --tablefile <output.txt>'
- H <mean> +- <std>, H Mean Rectified Surface
Integral
The Mean curvature values were compute by the
command,
'mris_curvature_Stats -l <label> -g -n -m -f
white -o <output.txt>
<subject> ?h'
I analyzed the each value. The ?h.Curv mean (within
the label) has opposite
relationship with Z value compared to MeanCurv,
while similar relationship
with Z value compared to H <mean>.
I heard that the MeanCurv is the integral of the
rectified mean curvature of
white matter surface (1/r mm), and ?h.curv is the
mean curvature of the
white matter surface with a Gaussian smoothing
kernel applied.
It looks that the MeanCurv and H Mean Rectified
Surface Integral has only
positive values, while the H <mean> and ?h.curv has
positive or negative
value.
I wonder whether MeanCurv and ?h.curv has the
difference meaning or
difference formula.
And I would like to know the meaning of the ?h.curv
negative value.
Is H <mean> ( by mris_curvature_Stats ) compute from
?h.curv ?
Thank you.
Han.
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