To add on to Bruce's explanation, the freesurfer parcellation atlas (which for example specifies the probability of precentral gyrus at a particular location) is not symmetric, thus it will treat the left and right hemispheres of your subject differently if you flipped it.
--Thomas On Sun, Jun 17, 2012 at 10:04 PM, Bruce Fischl <fis...@nmr.mgh.harvard.edu> wrote: > Hi Remmelt > > folding patterns are not symmetric across the hemispheres, so the cortical > parcellation will change if you flip things left/right, which is > appropriate. I would be surprised if you see much change in the thickness > though. > > cheers > Bruce > > > > > On Fri, 15 Jun 2012, Schur, Remmelt R. wrote: > >> Dear Freesurfers, >> >> Grey matter volumes of the same structure seem to be measured differently > > depending on if FreeSurfer establishes it as in the left or in the right > hemisphere. For example, if I take a look at the caudal anterior cingulate > in the right hemisphere and I flip the image (creating a mirror image of the > same hemisphere, which will then be treated by FreeSurfer as a left > hemisphere), the same structure has a totally different grey matter volume > (see attachment, on the right the original and on the left the flipped > version). Does anybody know what's the logic behind this and what's the best > way to avoid FreeSurfer creating asymmetry between left and right hemisphere > (maybe averaging flipped and non-flipped data?) >> >> >> Thanks! >> >> Kind regards, >> Remmelt Schür >> >> IMPORTANT WARNING: This email (and any attachments) is only intended for >> the use of the person or entity to which it is addressed, and may contain >> information that is privileged and confidential. You, the recipient, are >> obligated to maintain it in a safe, secure and confidential manner. >> Unauthorized redisclosure or failure to maintain confidentiality may >> subject you to federal and state penalties. If you are not the intended >> recipient, please immediately notify us by return email, and delete this >> message from your computer. > > > _______________________________________________ > 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
