Reactions to MRI with contrast?

I am having a lumbar MRI with contrast tomorrow morning. I've had 2 or 3 of the same MRIs before, but never with contrast. I am allergic to iodine, which the MRI center said is not in the contrast dye. I am also allergic to many things, including all types of hair dye, certain medications and food. I have been reading a lot about the contrast MRIs and seeing that a lot of people have had bad reactions. Should I insist on havin the MRI without contrast? I am very nervous, and any advice would be greatly appreciated!