[Freesurfer] Hide small cluster in FDR corrected map

Hi list, I have performed a seed-based fcMRI analysis by FAST.After mri_glmfit, I have obtained a sig.nii.gz which contains uncorrected results.I have corrected by FDR using the graphical interface provided in tksurf.The FDR corrected contains some very small areas (<5-10 voxels) which I would like to hide in order to present a more clear map.How is possible to do it?I have tried with mri_surfcluster.To have vwsig.nii.gz I should have a CSD file.But this file could be also produced when FDR correction is applied?I'm very confused.Please, could you help me because from several days I'm trying to have a solution.Thank you very much for your work.Kind regards. Stefano