23 Apr
2013
23 Apr
'13
1:27 a.m.
Hi Daniel
for the aparc.a2009 atlas :
- The average convexity sulco-gyral threshold vas usually set to 0 for the lateral cortex, and to 0.18 for the medial cortex.
- The average convexity value was negative for the whole insula (located deeply in the lateral sulcus/fossa). For the insular region, we used the mean curvature in a similar way: vertices with a positive mean curvature value were considered sulcal, and vertices with non positivevalues were considered gyral.
for more detail you can have a look to Destrieux C, Fischl B, Dale A, Halgren E. Automatic parcellation of human cortical gyri and sulci using standard anatomical nomenclature. Neuroimage 2010; 53: 1-15.
cheers
--
Christophe Destrieux,
Directeur du Département Communication et Multimedia
http://med.univ-tours.fr/M0S01/0/fiche___defaultstructureksup/&RH=120065...
Unité « Imagerie et Cerveau » UMRS INSERM U930, Université François Rabelais de Tours
http://www.u930.tours.inserm.fr/
Service de Neurochirurgie
et Laboratoire d'Anatomie - Faculté de Médecine - 10 Bd Tonnellé
37032 Tours - France
tel (33) 2 47 36 61 36 - fax (33) 2 47 36 62 07
----- Mail original -----
> De: "Daniel Yang" yung-jui.yang@yale.edu
> À: "Bruce Fischl" fischl@nmr.mgh.harvard.edu
> Cc: freesurfer@nmr.mgh.harvard.edu
> Envoyé: Lundi 22 Avril 2013 23:31:36
> Objet: Re: [Freesurfer] Where does a sulcus end and a gyrus begin in FreeSurfer?
>
> Thanks, Bruce!
>
> The average-convexity-crossing-zero idea makes good sense.
>
> Also I can see the segmentation/parcellation label in tkmedit when I
> move
> my cursor. That makes it clear which label is which.
>
> Best,
> Daniel
>
> --
> Yung-Jui "Daniel" Yang, PhD
> Postdoctoral Researcher
> Yale Child Study Center
> New Haven, CT
> (203) 737-5454
>
>
>
>
>
>
> On 4/22/13 5:01 PM, "Bruce Fischl" fischl@nmr.mgh.harvard.edu
> wrote:
>
> >Hi Daniel
> >
> >we have had various neuroanatomists make that decision, but the
> >typical
> >measure used is the average convexity or sulc (stored in ?h.sulc).
> >Where
> >it
> >crosses 0 is where the changeover is usually deemed to be
> >
> >cheers
> >Bruce
> >
> >
> >On Mon, 22 Apr 2013, Yang, Daniel wrote:
> >
> >> Dear FreeSurfer Experts and Users,
> >>
> >> This is probably a basic question, so please bear with me.
> >>
> >> I'm looking at the Coronal view in tkmedit, and I am wondering how
> >> does
> >> FreeSurfer knows where a gyrus ends and a sulcus begins (and vice
> >>versa).
> >>
> >> For example, I'm looking at the superior temporal sulcus. But I'm
> >> not
> >>sure
> >> how FS figures out which part is superior temporal gyrus, middle
> >>temporal
> >> gyrus, or superior temporal sulcus?
> >>
> >> Thanks!
> >> Daniel
> >>
> >>
> >>
> >>
> >>
> >
> >
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