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.
_______________________________________________
Freesurfer mailing list
Freesurfer@nmr.mgh.harvard.edu
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
The information in this e-mail is intended only for the person to whom it is
addressed. If you believe this e-mail was sent to you in error and the e-mail
contains patient information, please contact the Partners Compliance HelpLine at
http://www.partners.org/complianceline . If the e-mail was sent to you in error
but does not contain patient information, please contact the sender and properly
dispose of the e-mail.
