Hi 

I have a few questions regarding the use of “mri_volcluster” for clusterwise thresholding. Essentially, we have a volume of  pvalues obtained from a two tailed t-test comparing beta values from condition A vs condition B.

 

When I ran this command:

mri_volcluster --in transformedP.nii --sum cwthres_sum.txt --sign abs --fwhm 6 --mask avgmas.nii --cwpvalthresh 0.05 --thmin 2.3 --cwsig cwthresclusters.cwsig.nii

 

I got this error message:

ERROR: you must specify a pos or neg sign with --fwhm

 

Input was –log10(p-value)

Thmin was –log10(primary p threshold)

 

Is there a way to perform clusterwise thresholding on results from two tailed tests? Is it essential to use –log10(p) values as input?  Can I use raw t-values or any other values as input and thmin instead?

 

Finally, are there any papers/references which this command is based on?

Many thanks!