Yes, my after-treatment care sheet said to be sure and inform my physician if I was going to be having a chemical peel or MRI.
Apparently, some dyes contain iron oxide and can convert the radio-frequency pulses into electricity. I guess you could get a pretty good burning sensation (and I think I'm in pain now). The colors that seem to have the iron oxide are brown, some blacks, red, yellow and flesh. Mine's a smokey grey mixed with blue, so I don't know how much iron oxide that might have.