I had a question regarding to use 3dBlurToFWHM on PET images. The command is like below:
3dBlurToFWHM -input wpet.nii -prefix wpet_sm.nii -mask wpmask.nii -FWHM 8
After smoothing, 3dFWHMx reported to the following smoothness instead of 8mm:
3dFWHMx -arith -mask wpmask.nii ./wpet_sm.nii
++ 3dFWHMx: AFNI version=AFNI_2008_07_18_1710 (Nov 5 2009) [64-bit]
++ Number of voxels in mask = 264985
*+ WARNING: removed 11 voxels from mask because they are constant in time
12.3708 13.7532 13.7407
On the contrary, the measured smoothness is very close to the target of 3dBlurToFWHM for my fMRI images. Am I missing something?
Thanks!
