That question is above my pay grade. Assuming the implant is metal, we all know what happens when magnets come within the vicinity of metal.
It would depend on what kind of metal, I would assume a biocompatible, non ferrous alloy. The bigger problem could be that eddy currents induced in the metal could make it heat up in the intense fluctuating magnetic fields in an MRI. You wouldn't want her to suffer a brain sizzle.
Yes I know .. and I'm am sure hospitals incur this problem and work around it
But like you .. that info is above my pay grade and I don't have the answers