Arri London wrote:

> The usual contrast agents for MRI contain gadolinium. However some CT
> contrast agents can contain iodine.
> Haven't yet had a bad reaction to the MRI agent but did have one to the
> CT agent by the third go-round.

Sometimes the value of the test has to be weighed against the risk of
contrast. We can load 'em up with IV Benadryl and other things to lessen
the allergic response.