> I also figure that if I’m ever incapacitated and put in an MRI machine without the ability to give the doctor any forewarning, a tiny magnet getting ripped out of my finger will be the least of my concerns.
It might be a rather bigger concern for the owner of the MRI though...
The thing is half the size of a grain of rice, and isn't such a strong magnet. I don't think it's gonna cause major damage. Wheelchairs or oxygen tanks cause damage. Quarters and dimes are just annoying and need to be fished out.
(This my recollection from my friends who've done research with MRIs. I have no first-hand experience with them except once as a patient.)
Won't they get some metal detector over your first? Who knows you might just, let's say, have a magnet in your little finger! But seriously, there are more metal things under your skin possible, so if you can't make them 100% sure nothing is going to happen when they turn it on, I guess they will find out by themselves beforehand.
My dad's a radiologist and I've never seen anyone get metal detected prior to an MRI. Maybe they have one for unconscious ER patients, but I've never heard of it.
It might be a rather bigger concern for the owner of the MRI though...