Dear FSL experts,
I was running TBSS analysis using DTI data acquired from 5 control subjects
and 3 subjects with mild traumatic brain injuries. All the preprocessing has
been done using FSL4.1.2 .I am interested to identify the regions where FA,
MD and transversal diffusivity indicate differences between two groups. For
randomisation procedure I used first TFCE option .As a result FWE corrected
shows the results only for MD. I couldn't obtain FWE corrected for multiple
comparisson for FA and transversal diffusivity using TFCE option. Also I
was trying randomisation using cluster-based thresholding corrected for
multiple comparisons setting different values for threshold but I couldn't
obtain corrected values for p maps in a range [0.95,1]. Based on the
hypothesis that regions such as corpus callosum, anterior and posterior
limb of internal capsule are more vulnerable to traumatic brain injuries I
was interested to testing this hypothesis for spleninum of corpus callosum.
1)I'm wondering if this is legal, to limitate TBSS analysis to some specific
region in the brain.
2)If it is, could you please check if it's correct
draw a mask of spleniunm of corpus callosum (mask_SCC)
fslmaths mask_SCC -mas mean_FA_skeleton_mask mask_SCC_new
randomise -i all_FA_skeletonised -o tbss -m mask_SCC_new -d
design.mat -t design.con -n 500 - -T2 -V
As a result of permutation, corrected p image tbss_tfce_corrp_tstat1 with
values [0.95 1] indicate a reduction of FA in mild traumatic brain injury
group in spleninum of corpus callosum.
3)I'm wondering about the validity of the previous steps.
If this is valid, why this result didn't come up by using the
mean_FA_skeleton_mask as the mask to feed into randomise.
4)Another concern is related to the new version v2.1 for randomise. I did
the same analysis for the same subjects using FSL4.1.1 randomise v 2.0 and I
was able to have more results . What is the explanation? Which one is more
recommended?
I'm so sorry for the basic questions. Any suggestions will be greatly
appreciated.
Many thanks in advance.
Best Regards,
Angelica
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