3dSatCheck exists, but is not compiled in AFNI binary distributions. I'm not sure it is particularly useful. At the moment I wrote it, my idea was that people would need a way to check for pre-steady state in their data. However, my love for this idea waned quickly, as I now feel that people should LOOK at their data to get an idea of how much pre-steady state (pre-saturation) artifact is present at the start of each imaging run. If you have a study with all data acquired under the same scanning protocol, all EPI datasets should be pretty much the same in this regard.

3dSatCheck -help output

Quote
Myself
Usage: 3dSatCheck dataset [...]
Prints the 'raw' initial transient (saturation) check
value for each dataset on the command line. Round this
number to the nearest integer to get an estimate of
how many non-saturated time points start a dataset.

Sample run:

Quote
and I
3dSatCheck v?_time+orig.HEAD
++ v1_time+orig.HEAD = 0.667
++ v2_time+orig.HEAD = 0.619
++ v4_time+orig.HEAD = 1.592