Dear FSL experts,
I was running TBSS analysis using DTI data acquired from 5 control subjects
and 3 subjects with mild traumatic brain injuries. I used FSL4.1.2 version
for all preprocessing of the data including TBSS analysis.I am interested
to identify the regions where FA, MD and transversal diffusivity indicate
differences between the 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 another option,
cluster-based thresholding corrected for multiple comparisons using
different values for threshold .For FA and threshold c = 4, the p image,
tbss_clustere_corrp_tstat2 ,has a p values corrected above 0.928 which is
not in the range 0.95-1.Also for a threshold of 0.3 the corrected values is
in range 0.95-1.
1)I'm wondering if this threshold value of 0.3 is valid or is to low?Is it
possible a way to calculate the thershold?Is it a paper or manual, to
clarify, I'm sorry for missing .Also I'm wondering if the output of TFCE
uncorrected data can be fed into FDR correction.
2)If yes, could you please take a look to see if it's correct:
fslmaths tbss_tfce_p_tstat2 -mul -1 -add 1
tbss_inv_tfce_p_tstat2
fdr -i tbss_inv_tfce_p_tstat2 -m tbss_tstat2 -q 0.05.
3)I'm not sure what mask image is in -m option.
4)Could I apply FDR correction to output from cluster based thresholding ?
5) Is it recommended in this case to randomise using
cluster-based thresolding corrected for multiple comparison using cluster
mass -C option? What should be the values for C in this case?
Any suggestions will be greatly appreciated.
Many thanks in advance.
Regards,
Angelica
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