A few years back when I had the ct scan for thymus, it was the ct tech who said they would need to take extra precautions because I might be myasthenic and more susceptible to a bad reaction to the dye.

They used a pediatric solution (a much lower iodine concentration), put it in much more slowly, and had a resident right there as the dye was administered in case there was a problem!! They were freaking me out - - but it was the beginning of my realizing that I had to be more educated and more careful.