I have a magnet implant and looked into this. I found a study about MRIs and cochlear implants and not once did the study mention any dangers. Instead their concerns were based on demagnetizing the implant, and they found that the risk of demagnetization could be mitigated by aligning the patient in a certain way.

I know that cochlear implants are very different from finger magnets (cochlear implants are attached to bone) but it does challenge some of my basic assumptions.

It should also be noted that it would take less than five minutes to remove the implant with a scalpel.