This is one to know about and avoid if you can. Gd, atomic number 64, is a rare earth metal. Apparently it has a number of uses but the one you might encounter is a contrast “agent” used with MRI procedure. Supposedly it is quickly eliminated if your kidneys are good. Some can tolerate and others have long lasting effects as (per the FDA) Gd may remain in your body. Don’t expect your hospital people to warn you of the possible danger because they probably won’t!