yes, it's a somewhat different and more conservative test. I guess you
could check the talairach transforms of some of your subjects with eTIVs
that don't make sense (or change the most over time) to try to see why
this is happening. Or take Mike's suggestion and test a different (but
probably still interesting) hypothesis
On Sun, 21 Feb 2016, Angela Favaro wrote:
Hi, thank you
I think this would test something different: 'how much a brain area is
atrophic controlling for the average brain atrophy' and not 'how much
a brain area is atrophic controlling for the individual differences in
head size'. Doesn't it?
Angela
"Harms, Michael" <mha...@wustl.edu> ha scritto:
Hi,
Why not use a measurement of brain size rather than “eTIV”?
cheers,
-MH
--
Michael Harms, Ph.D.
-----------------------------------------------------------
Conte Center for the Neuroscience of Mental Disorders
Washington University School of Medicine
Department of Psychiatry, Box 8134
660 South Euclid Ave.Tel: 314-747-6173
St. Louis, MO 63110Email: mha...@wustl.edu
On 2/21/16, 6:06 AM, "freesurfer-boun...@nmr.mgh.harvard.edu on behalf of
Angela Favaro" <freesurfer-boun...@nmr.mgh.harvard.edu on behalf of
angela.fav...@unipd.it> wrote:
there is a mistake in the graph, hippocampal volume is TIV2
I apologize for that!
Angela Favaro <angela.fav...@unipd.it> ha scritto:
Hi Bruce,
please find attached the graph of the correlation between the two time
point. I did not find outliers or failures. However the discrepancy
between TIVs is particularly high in few cases. Obviously these data
are those before running longitudinal streaming
This is a sample of adolescents with low body weight (anorexia nervosa).
In my previous study (on young adults with low weight) I found no
correlation between TIV and body weight and high correlations between
fs estimated TIV and manually segmented TIV (r=0.94 in the whole
sample and r=0.93 in the underweight sample (n=38)).
Do you think that the young age can be a factor? or patients who are
more acutely underweight?
Thank you for any suggestion
Angela
Bruce Fischl <fis...@nmr.mgh.harvard.edu> ha scritto:
Hi Angel
the time1/time2 correlation of eTIV is pretty worrisome. Are you sure
that there aren't outliers/failures in that set?
Bruce
On Sun, 14 Feb 2016, angela.fav...@unipd.it wrote:
Dear Freesurfer experts,
I have a question about eTIV (FS 5.3) which I use as a covariate where
appropriate. Is it in some way influenced by the presence of brain
atrophy?
I have a new sample of subjects in a longitudinal study: at time 1 they
have some atrophy (due to low body weight) that improves in time 2 (4
months). I observed that eTIV-time1 is slightly correlated with weight
(r=0.3) whereas no correlation is present at time 2. The correlation
between eTIV-time1 and eTIV-time2 is somewhat lower than expected
(r=0.53)
and is lower than correlation between SegBrain_Vol_1 and SegBrain_Vol_2
(0.65).
Do you suggest in these cases to perform manual segmentation to obtain
TIV? or is there any other method (in freesurfer) to obtain an
estimate of
TIV not influenced by brain atrophy? What about using BrainMask_to_TIV?
Thank you for any suggestion
Angela
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