Hi Dana, You should use the -T, as the -T2 gives some extra emphasis on cluster extent, which is a feature useful for TBSS. Although inferences using --T2 for VBM are certainly valid, the extra weight to cluster extent isn't what your readers are expecting to see. All the best, Anderson On 16/01/2014 19:07, Dana Wagshal wrote: > Hi FSL group, > > I accidentally used --T2 for my VBM analysis. Is this ok to do or is it absolutely necessary to use the -T flag?