>Are there any pathologies out there that causes sprouting of new brain tissue?
Yes, abstinence;)
Cheers-
Andreas
________________________________________
Von: FSL - FMRIB's Software Library [[log in to unmask]] im Auftrag von Jesper Andersson [[log in to unmask]]
Gesendet: Mittwoch, 27. Mai 2009 13:36
An: [log in to unmask]
Betreff: Re: [FSL] Sienar Vs FSL-VBM
Dear Antonios,
> I have some questions regarding the similarities and differences
> between
> SIENAr and FSL-VBM.
>
> Correct me if I'm wrong , SIENAr will measure group differences only
> in gray
> matter areas which are located in brain edges or very close to brain
> edges
> (since flow images are dilated) while from the other side FSL-VBM is
> able to
> measure differences in all gray matter voxels defined by the gray
> matter
> mask (produced in the first stages of VBM's analysis). So a direct
> comparison of voxelwise changes -with both methods in a specific
> data set
> for gray matter differences- will not present any overlapping areas
> (except
> only from the brain edges). Is my assumption correct?
SIENAr will only detect changes on/very near the cortical surfaces and
at the CSF-white matter junctions of the ventricles. It is
specifically designed to look for atrophy, so that is hardly a
limitation since those changes will manifest themselves primarily at
those surfaces.
> However in SIENAr there's a possibility to identify if a group
> difference is
> caused by atrophy of the first group or growth of the second one or
> both
> phenomena take place together. Is there any possibility in FSL-VBM to
> disambiguate what's going on in areas identified with group
> differences?The
> statistics produced after vbm analysis only depict (the areas and) the
> significance of differences among the groups but not what actually
> goes on
> there.
That is not correct. FSL-VBM is a more generic tool than SIENAr, and
can be set up to answer much the same questions. For SIENAr you will
need two time-points per subject, which is what allows you to compare
changes-over-time between groups. If you have the same data (i.e. two
time points per subject) you can set up an FSL-VBM analysis to look
for time-by-group-interaction, which will pose much the same question
as SIENAr does.
Also, would this really be an issue? Are there any pathologies out
there that causes sprouting of new brain tissue?
Good Luck Jesper
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