Hi Alan & Knut, Isn't GI a function of surface area, i.e. GI = SurfaceAreaPial/SurfaceAreaHull, e.g.:
http://www.frontiersin.org/files/Articles/668/fninf-03-025/image_m/fninf-03-025-g003.jpg The hull area (denominator) normalizes for scale, so I would not expect the GI and surface area to be in lock-step, unless I had normalized the surfaces to some stereotaxic space first, which is not typically done. (Even then, that's not the same as making all denominators equal across subjects/hemispheres.) Donna On Oct 6, 2014, at 6:30 AM, Alan Francis <alandarkene...@gmail.com> wrote: > Hi Knut: > > Gryification and Surface Area are two completely different things. Surface > Area, as measured by FreeSurfer, gives you the area of the surface (roughly > length x breadth) of a given region of interest: e.g., Pars triangularis. It > is measured in millimeter squared. > > Gyrfication index, by contrast, measures the depth of the each gyri and is > done after you have completed the FreeSurfer Recons. You can find more > details on gyrification at the following website: > > https://surfer.nmr.mgh.harvard.edu/fswiki/LGI > > This explains the whole concept of gyrification. > > best, > > Alan > > On Sun, Oct 5, 2014 at 11:51 AM, Knut J Bjuland <knutjor...@outlook.com> > wrote: > Dear FreeSurfer experts > I have run analyses on gyrification index. I was wondering if anybody could > tell me what exactly is the relationship between gyrification index and > cortical area. My gyrification results and area results are to a large extent > similar. Am I measuring approximately the same thing? > > Thank you > Knut Jørgen Bjuland > PhD candidate > The Norwegian University of Science and Technology (NTNU) > Trondheim, Norway > > _______________________________________________ > 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. > > > _______________________________________________ > 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. _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
