Dear Bruce, Thank you for your response regarding high area values.
I have indeed observed high values (I.e. >20) in both the white and pial surfaces of my subjects, albeit only at a few vertices. The vertices indices that contain the highest values in these surface appear around ~258,000-324,000. Would you consider this the end of the array? And if not, what could cause a value of ~80 in the ~258,000 vertex of a pial surface reconstruction? As a background to what I¹m hoping to accomplish: I am using Freesurfer features (arrays) as inputs for pattern classification, therefore I am interested in potential impact on my models due to these outliers. Smoothing reduces the effect of these outliers, however also raises the values of surrounding vertices. I am thinking of replacing these high values with an average area measure taken across all participants prior to smoothing. Again, thank you for your insights in this topic. Best, Derek ________________________________________ Derek Sayre Andrews, MSc PhD Candidate & IoPPN Student Forum Chair Department of Forensic and Neurodevelopmental Sciences & The Sackler Institute for Translational Neurodevelopment Institute of Psychiatry, Psychology & Neuroscience, King's College London Telephone: +44 (0)20 7848 5701 Email: derek.andr...@kcl.ac.uk On 25/09/2015 17:00, "Bruce Fischl" <fis...@nmr.mgh.harvard.edu> wrote: >are they only high on the pial and not on the white? I would have guessed >that they would be high on both, and further that it is due to the >topology >correction and the quirks of the way we retesselate. One easy way to find >out if this is true is if the vertex index is near the end of the list >(i.e. close to the total number of vertices, since the vertices added >during the correction are at the end of the array) > >cheers >Bruce > >On Fri, 25 Sep 2015, Andrews, Derek wrote: > >> Dear FreeSurfer Support Team >> >> First of all, I must thank you for your excellent software! >> >> I have been looking at distributions of various free surfer features >> (histograms of the vertex wise measures). I have noticed some high >>values >> among the pial and white matter surfaces, these values range from 20-85. >> Again, this in only in a handful of vertices (out of millions of >>measures). >> I am wondering what could account for such a high value? >> >> Thank you for your help in clarifying this. >> >> Best, Derek >> >> >> >>_________________________________________________________________________ >>___ >> >> Derek Sayre Andrews, MSc >> PhD Candidate >> >> Department of Forensic and Neurodevelopmental Sciences & >> >> The Sackler Institute for Translational Neurodevelopment >> Institute of Psychiatry, Psychology & Neuroscience, King's College >>London >> >> Telephone: +44 (0)20 7848 5701 >> Email: derek.andr...@kcl.ac.uk >> >> >> >>_______________________________________________ >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
