By the way, smoothing can remove the thickening (if there is only a little and mainly thinning ).
Best, Martin On 08/05/2013 02:18 PM, Martin Reuter wrote: > Hi Bastian, > > actually (see other mail today) it computes percent thickening per year > as it is the slope of the linear fit into the measurements (thickness > with respect to age or time). If the slope is negative, there is thinning. > > The results (within subject and on fsaverage) have signs so they always > reflect both thinning or thickening. And usually due to noise you'll > find regions in an individual subject that go both ways. > So when you look at the within subject results (on the base anatomy) you > should see both blue and red regions. that should be also true for when > looking at the same map on fsaverage (it is just mapped there, should > not change the sign, only the location a little). > > Best, Martin > > On 08/02/2013 05:31 AM, Bastian Cheng wrote: >> Dear freesurfer-experts, >> >> I have successfully done a longitudinal analysis on cortical thickness >> changes over 2 timepoints (0 and 1 year). >> >> My question is: >> >> If I look at the -individual- overlays of perc. change (i.e. pc1fit), >> only positive values are shown. >> whereas at the -fsaverage- view, positve AND negative values are shown >> (i.e. thinning and thickening) >> >> I understood that long_mris_slopes calculates the "percent thinning per >> year". >> But is there a way to show both sides of the histogramm (i.e. from -2 >> to +2) also on the -individual- overlay? >> >> This might be a naive question, however, any help is greatly appreciated! >> >> Bastian. >> _______________________________________________ >> Freesurfer mailing list >> Freesurfer@nmr.mgh.harvard.edu >> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >> >> -- Martin Reuter, Ph.D. Assistant in Neuroscience - Massachusetts General Hospital Instructor in Neurology - Harvard Medical School MGH / HMS / MIT A.A.Martinos Center for Biomedical Imaging 149 Thirteenth Street, Suite 2301 Charlestown, MA 02129 Phone: +1-617-724-5652 Email: mreu...@nmr.mgh.harvard.edu reu...@mit.edu Web : http://reuter.mit.edu _______________________________________________ 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.
