Hi Martin,
Sorry for the delay.
As for the defaults: the main (and almost only) parameter is the size
of the circular region of interest, which you can change if you want.
There is a discussion about the rationale for choosing a radius
between 20 and 25 mm in the IEEE TMI validation paper (which you will
find on the wiki). The main purpose of the LGI was to be sensitive to
changes on the level of a few sulci and gyri (which was chosen given
the variability in sulcal configuration). If you suspect small gyral
changes, you can try to set the radius at 10-15mm or so, I will be
interested to know the results you can have in your cohort with small
radii.
We did not try in neonatal brains (our youngest patients are 6, for
which it is perfectly fine to use "adult settings"). The first
obstacle that I would imagine is the accuracy of cortical
reconstructions in such brains. Then I would imagine that you need a
smaller radius for the circular region of interest in neonatal than
in adult cortex, and also that you would need to try a few radii
before finding the optimal one... Again, I would be happy to know
your observations on that!
Marie
On 24 sept. 08, at 20:15, Martin Kavec wrote:
Hi,
I wonder how are the default FS settings to calculate LGI
finetuned? More
towards large-scale changes, such as in neonal>pediatric cortex, or
would it
be possible to study rather focal changes, say on a sulcus/gyrus
level? Which
parameters should I change to become sensitive to "smaller" LGI
changes?
Thanks a lot for input,
Martin
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