Ct showed dilated ureter possibly megaureter 5 yrs ago.nephrologist not worried.different dr.ordering 2 mri w/contrast.is contrast concern for kidney?

Maybe: Gadolinium the contrast agent used for MRI is not be used if the kidney function is low ie GFR less than 30. Otherwise it is probably ok.

Wrong study: Nephrologist likely knew what s/he is doing. A mag3 nuclear renal scan would be the correct test to evaluate comparative function between left ; right ; degree of obstruction present. Not mri. Ordering dr. Either does not know what s/he is doing or worse has a financial stake in the mri. Would be worth reporting to state medical board of registration if the latter.

MRI contrast: The contrast used for MRI is gadolinium. It is not toxic to kidneys. CT contrast is toxic to kidneys. IVP contrast is toxic to kidneys.