Hi,
I have a large single, large cluster (1000+ voxels) present after TFCE
correction at 0.001. To explore this further I want to run some
tractography from it. As the cluster is so large tractography just using
this cluster is difficult to interpret, and selecting the COG or voxel with
peak p/t value within this cluster would lose a lot of information.
In order to break down the cluster into smaller clusters and seed from them
I was wondering which of the following would be most valid or whether they
would give the same result:
Approach 1:
a) Take corrp image (image A) and apply clustertool using parameter settings
that break it down as much as possible (eg high threshold and low
connectivity value)
b) Mask zmax voxels in each cluster onto original corrp image (image B) --
ie left with an image of zmax voxels for each cluster
c) Deproject and backnormalise image B
d) Create a small sphere aournd the voxels in image B and use as seeds
Am I right in thinking this might not work as step c) may not result in
single voxels in native space for each cluster? (ie in deproject the no of
of voxels in the input does not equal the no in the output)
Approach 2:
As above but create sphere before deprojection and back normalisation -
might this have problems if the sphere lies off the group skeleton ?
Approach 3:
a) Take corrp image (image A) and deproject into each subject
b) Then apply clustertool with the same threshold and connectivity
parameters to each subject
c) Within each subject only accept clusters over certain size eg 10 voxels
d) Within these clusters take zmax voxel and create sphere of set radius
around them
e) Now backnormalise all clusters into native space and use as seed in each
subject
Or perhaps someone might have a much better suggestion ?
Thanks.
Mark
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