Howdy-
Just to note, the magic of internal t-to-p (and vice versa) calculations is not limited to BRIK/HEAD datasets; NIFTI datasets can have this happen, as well.
AFNI statistics program populate AFNI header fields that contain degree-of-freedom (and other stats label) information, and that is what is used. These include BRICK_STATAUX and BRICK_STATSYM. The FDR curve is created in a similar way, and populates information in fields such as FDRCURVE_000000, etc. The AFNI header is storable within NIFTIs, and hence both BRIK/HEAD and NIFTI files can contain this information.
Can I ask what kind of statistic you have, and perhaps where it was calculated (presumably, not an AFNI program if that information hasn't been propagated)?
--pt
