Why did you say you took them off for an MRI?
One time I was having carpel tunnel surgery and when the nurses saw them, they freaked out and said I was going to get electrocuted, or something, but my doctor said that wasn't true at all (she originally thought they were those bracelets people wear to help with arthritis or general well being lol) so I left them on, with no worries.
The only problem with these bracelets (I have the old ones) is how hard it is to take them off, and although it is possible, I don't want to wear out the screws, taking them on and off, every time I have an X-ray or something…