My sister is going to have an mri of her breasts. she only has one kidney and does not want to have the gadolinium contrast injected. alternatives?

Unfounded anxiety.: There is no significant risk of renal toxicity with MRI contrast. The MRI contrast is not the same as CT contrast, which does have a risk of renal toxicity. The only renal issue with MRI contrast is in the setting of renal insufficiency/failure, in which case MRI contrast increases the risk of nephrogenic systemic fibrosis. If her renal function is normal, there is no risk of that either.

Gadolinium: With kidney compromise, gadolinium is not recommended, but if kidney function (generally measured by glomerular filtration rate: GFR) is normal with the functional kidney, the effect is minimal. Consult the radiologist who is evaluating the MRI for alternatives/recommendations.