Dear fsl users,
After evaluating the resulting GM_mod_merg file from the use of
fslvbm_3_proc script I've noticed that 4 volumes out of 47 in this file are
distorted. How should i cope with this issue? Can I continue the analysis
(randomise script) with these vols included or this can affect the validity
of my results? If I have to exclude these volumes which is the best way to
be done cause I don't think it's a good idea to exclude the initial
'problematic' files and re-run all the vbm's steps from scratch.
The intensity range of the GM_mod_merg file is around [0 1.4]. Is this a
normal range of values? What kind of values does a GM_mod_merg file
represents? They are not t-values right?
The values of GM_mod_merg_s*.nii.gz represent the same values as GM_mod_merg
but under smoothing with different kernel sizes, right? Why do we need these
files(GM_mod_merg_s*.nii.gz) since GM_mod_merg_s*_tstat.nii.gz images are of
our interest?
Regarding the decision for the most appropriate smoothing, a relevant
discussion in the forum (Subject: RE :[FSL] FSL_VBM selecting a mod_merg
file) was mentioning that it would be better to choose a small smoothing
kernel when we search for small brain changes (like in controls group) and a
big one when we expect big changes ( like in patients' group). I'm bit
confused here... Since all subjects (controls-patients) are merged together
in the GM_mod_merg_s*.nii.gz and will be used for further analysis with
randomise how can we decide for the most appropriate value?
Thanks a lot
Antonios-Konstantinos
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