Hi Alex,
we've fixed a couple of small discrepancies in mris_anatomical_stats. I
would use the new version - it should be fine on old surfaces.
Bruce
On Tue, 27
Sep 2005, Fornito, Alexander wrote:
HI,
I'm finishing a study I completed using an older version of freesurfer
(20040218), and have noticed that I get different values for surface area and
grey matter volume when using mris_anatomical_stats for my labels depending on
whether I use the mris_anatomical_stats that it is part of this older
distribution, or the one packaged as part of the newer dev release (20050905).
I noticed on a previous posting that Doug Greve identified an error with
respect to how surface area was calculated (I've included it below) and was
wandering if this is the reason for the discrepancy.
Should I believe the figures calculated using the newer version, or will this
also be associated with errors, since the surfaces were generated using the
older version?
Thanks,
Alex
I have just fixed a bug in FreeSurfer that involves computing the area
of some surface structures. For those of you who care, this was a bug
that emerged after converting our surface meshes from quadralaterals
to triangles. This change was made a few years ago.
This change should have little effect on the reconstruction. It will
have an effect on programs that report the area of subsections of
cortex (but not total cortical area). At least three such programs
that are affected are: mris_compute_overlap, mris_label_area, and
mri_surfcluster. The bug causes the reported area to appear to be 1.5
times what it really is. For example, in mri_surfcluster, a cluster
threshold of 300 mm^2 would actually be a threshold of 200 mm^2.
For those in the NMR center, these three programs have been
updated. For those outside, you can get these programs from
ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve
New versions of freesurfer will, of course, have the update.
Sorry for any inconvenience.
doug
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