Thanks so much Rick!

If I understand correctly, there's a suggested relative ordering between time shifting and volume registration (based on the observed detrimental effect of one on the other) and a relative ordering of despiking and time shifting (with a more theoretically grounded reason):

TS < VR
DS < TS

I had been under the impression that there was also a basis for performing vol reg before despiking: something about how despiking can cause artifacts near tissue boundaries that makes volume registration harder:

VR < DS

Since these are contradictory constraints, was it decided that the last was the least important to enforce? Or is that third one bogus?

While doing my analysis, I'm trying to get a theoretical justification for each stage as well as their ordering. Please pardon me if I'm still a little idealistic :)