Hi Bob,

Thanks very much for all your replies!

I think I am clear to some of my questions now. I am sorry for not providing some details before asking questions. Here is an example of "a very little difference" in the mean values between "3D+t Statistic" and 3dTstat for one voxel from my dataset: 979.2806 (given by "3D+t Statistic") and 978.98 (given by 3dTstat). These values were copied from the "Define Function" box. I am just curious because they are different.

I have gone through the -help output of 3dvolreg for several times and tried to use some options for registration. Sometimes it is hard to tell the difference between different options or different values for one option by visual check only. I just want to know which options are good for high resolution SPGR dataset and which ones are good for EPI dataset, as you mentioned in AFNI manual that in most cases "BK" is the best for functional dataset and "Li" is the best for anatomical dataset when warp them on demand.

Thanks again,
Xiangchuan Chen