@parrotqueen
I, too, had concerns over the use of a gadiolinum contrast dye (as I seem to react to so many agents) when told to get an MRI. I don't know whether this is helpful or not, but I learned that the FDA has approved nine different gadiolinum contrasts (GBCAs) in the U.S., one of which (gadobutrol or Gadavist) seems to have the least issues. It turned out that this is what was being used at my hospital, so I relented, and didn't have a problem.

I subsequently learned, however, with repeated GBCA administrations, gadiolinum can deposit in the brain, skin, bones, liver, and other organs, even if the patient has normal renal function. The clinical implication of the gadolinium deposition in the brain remains poorly understood and studied. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6158336/

And that's "the thing" for me: doctors prescribe a lot of procedures which haven't been well-studied, and they rarely understand the potential implications themselves. In the meantime, patients are left wondering if their part in all this is as guinea pigs. If I were in your shoes, I would grill my oncologist and head of hospital radiology on whether the MRI wouldn't be almost as effective without using the contrast agent.

Blessings to you on your difficult decision-making.