I am working in this field, so I am aware of nephrogenic systemic fibrosis as rare condition caused by Gadolinium contrast agents in people with kidney disease. As far as I know, there was no new case in the last 10-15 years after the took certain less-stable contrast agents from the market and assessing kidney function is also standard now. In the aftermath of this, scientists discovered that Gadolinium is retained in the body after MRI scans to a small amount. As far as I know there is no evidence that this causes any harm, but as I said, this is a concern and this is why it studied.