Hi Angela
gyrification is the ratio of areas and hence dimensionless, so I would
think it wouldn't be much affected by TIV.
cheers
Bruce
On Sun, 21 Feb 2016, angela.fav...@unipd.it wrote:
In the case of a gyrification analysis, does correction for total brain
volume make sense?
Angela
Inviato dal mio dispositivo Huawei
-------- Messaggio originale --------
Oggetto: Re: [Freesurfer] eTIV question
Da: Bruce Fischl
A: Freesurfer support list
CC:
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" 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" >> angela.fav...@unipd.it> wrote:
>>
>> there is a mistake in the graph, hippocampal volume is TIV2
>> I apologize for that!
>>
>> Angela Favaro 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 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
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Freesurfer mailing list
>>>>> Freesurfer@nmr.mgh.harvard.edu
>>>>>
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
>>>>>
>>>>>
>>>>>
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