Contrast agents are used in both MRI and CT, however MRI contrast does not contain iodine.
MRI contrast and CT contrast are differnt. CT uses iodine which is nephrotoxic. MRI uses gadolinium which requires kidneys to excrete it.
Gadolinium may be nephrotoxic. However, its biggest concern is that in patients with renal disease (both AKI and ESRD patients), the gadolinium doesn’t clear and can cause systemic sclerosis or nephrogenic systemic fibrosis (NSF).
Sample case.
I had a patient in the 70s that I ordered U/S kidneys because of Cr. of 1.65 and eGFR of 38. The U/S showed large liver masses that the radiology thought are likely mets and he recommended Multiphasic CT of abd with contrast. He wasn’t aware of his kidney function. I discussed with the radiologist and we ended up choosing MRI with contrast to evaluate his liver masses. The reasoning was that MRI contrast isn’t really nephrotoxic. The nephrogenic systemic fibrosis is a black box warning the FDA gives for patients with eGFR < 30. This patient’s GFR was 38 and so we chose MRI with contrast.
Reference
Curr Drug Saf. 2008 Jan;3(1):67-75. https://www.ncbi.nlm.nih.gov/pubmed/18690983