Gadolinium poisoning is possible from the MRI contrast agents. There's a chelator called NBMI (a.k.a Emeramide a.k.a OSR) that was invented by chemist Boyd Haley that can be used to chelate gadolinium.You should insist on not being injected with a contrast agent! Pictures should be possible without it. I was stupid and said yes to the injection. When I was laying there before(!) getting in the MRI, I got a burning pain in my chest by which even the doctor got concerned; but they didn't know what to do about it so we just went on.
The pain got weaker till it became "just" a strange sensation which disappeared after a few days. Nevertheless, Chuck Norris says his wife got heavily poisoned by multiple contrast agent injections (no joke, you can google it). It is some dubious stuff and should not be necessary.
He designed the molecule to bind to mercury and not unbind from it even if it takes months for the mercury to be excreted from the body because of impaired liver and/or kidney function, and it does that; the molecule's affinity for mercury is its greatest affinity, meaning it won't unbind from mercury to bind to anything else instead. It also has a high affinity for cadmium and lead -- I think maybe 2nd and 3rd most -- and so will bind to and stay bound to those unless it gets near a mercury that it'll drop the cadmium or lead to bind to instead. That means it is possible to have some redistribution symptoms from cadmium or lead if you have a lot of one or both of those and mercury, but if you can tolerate those symptoms then as the mercury is decreased there'll be less redistribution from binding then unbinding of cadmium and lead and the cadmium and lead will be preferentially bound because of the mercury not being an option. That's the theory of which metals will be excreted in what order because of the molecule's affinities -- that mercury will be bound and excreted first, then the metals of lesser affinities -- but in practice the NBMI molecules don't all get bound to mercury even if it's in the body and so mercury, cadmium, and lead are all bound and removed somewhat, mercury the most, and as the amount of mercury in the body decreases the cadmium and lead are bound more.
I forget what the affinity for gadolinium is, but lots of people have used NBMI to chelate it pretty safely. You just have to be aware that if you have lots of mercury, cadmium, or lead, it'll chelate those too and there might be some redistribution symptoms from that. But the redistribution risks from NBMI are much less than other chelators. There are lots of people who have had problems from redistribution from using other chelators who use NBMI to fix those. There's a Facebook group; search "NBMI Emermide".