Hi Ricardo we do individual subject-level estimation of levels. And it could be a confound I guess, although we use intensity gradients to definite boundaries not absolute intensity levels, so we might be less prone to this problem. If it shifts the apparent boundary there isn't much we can do about that though.
cheers Bruce On Tue, 9 Jun 2015, Ricardo Saute wrote: > Dear FreeSurfer experts, > Schwartz et al (Neuroimage 103, 2014, 192-201) have demonstrated that T1W WM > signal increases with increased body adiposity, probably due to altered > brain lipid composition. This would affect cortical thickness measurements > in one of two ways: overestimating, in algorithms using participant-specific > intensity levels to define WM and GM; or underestimating, in algorithms that > do not use participant-specific intensity levels for classification. So, > > 1. What kind of algorithm does freesurfer use to classify tissue (is it > based on participant-specific intensity levels?)? > > 2. Would increased T1W WM intensity and increased WM-GM contrast influence > cortical thickness measure? Would that be a confounder in my analysis of the > relationship between body adiposity and cortical thk? > > Thanks in advance, > Best, > Ricardo > > _______________________________________________ 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.
