Fwd: pars triangular and BA44 segmentation bug? - Freesurfer

11 Jul 2012


      Dear Bruce,
Did you also identified a strong rightward asymmetry (with pars triangular
and BA44) in your data analyzed by freesurfer 5.1? Just, to be sure, that
this is not an issue only with our data. I'd like to use the TRACULA as
well, and because tracula uses the cortical parcellation of our subjects
I'm not sure that it is worth to start TRACULA now, or waiting for your
cortical parcellation fix.
Sorry for disturbing you again with the same issue, but it is very
important for us to know, that it is a real issue with the cortical
parcellation or we messed up something, and if it is a real issue, which
labels we shouldn't use for statistical analysis.
Thank you in advance for your answer,
Gabor
2012/6/25 Bruce Fischl fischl@nmr.mgh.harvard.edu
...
sure. Thanks for pointing out the BA44 issue.  We'll put together a fix in
the next couple of weeks
Bruce
On Mon, 25 Jun 2012, Gabor Perlaki wrote:
Dear Bruce,
...
I've checked the pars triangularis. It was right-lateralized in 79
subjects
and left-lateralized in only 19 subjects.
Thanks, Gabor
2012/6/23 Bruce Fischl fischl@nmr.mgh.harvard.edu
      the structures don't need a threshold. Do you know that pars
      triangularis is left lateralized? For the BAs will get you a
      solution
  On Sat, 23 Jun 2012, Gabor Perlaki wrote:

        Dear Bruce,

        We don't used any thresholding by ourselves, we just
        took BA44 volumes out
        of the text-file in the stats directory.
        Should we use thresholded values instead of the
        volumes reported by the text
        files in the stats directory?
        Could we use the volumes reported by the aparc.stats
        and aseg.stats files
        for any statistical analyses, or do we need
        threshold that structures as
        well?


        Thanks,
        Gabor

        2012/6/23 Bruce Fischl <fischl@nmr.mgh.harvard.edu>
             Hi Gabor

             are you thresholding the BA4 label? In 5.2 we
        will distribute
             some tools to automatically threshold the
        labels so that the
             predicted area has the average area of the
        input labels. The
             right BA44 had more spatial spread than the
        left, so you might
             be including a lot of low probability vertices.

             cheers
             Bruce

             On Sat, 23 Jun 2012, Gabor Perlaki wrote:

                   Dear Bruce,

                   In the paper "Left-right asymmetry in
        volume and
                   number of neurons in adult
                   Broca's area." by Katrin Amunts, 10
        subjects (5 men
                   and 5 women) were
                   studied, and the volume of BA44 was
        greater in the
                   left hemisphere than in
                   the right in all ten cases. So, it is
        very strange
                   that the volume of BA44
                   was greater in the right hemisphere in
        all of the 80
                   subjects analyzed by
                   Eniko.

                   Thanks,
                   Gabor


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