'Patient' is just a global term for all the groups, but is used to separate the human volunteers for phantom studies. I'm not sure where you are seeing "patient" (at LONI or at ATRI), so it might be used slightly differently between the two sites. In addition, I believe "paitent" vs. "volunteer" shows us in a few places, which difference ADNI human subjects, vs. human volunteers that were used for site qualification, e.g. qualifying the MR scanner.