Contrast Media for Dummies

Iodine contrast media in brain x-ray

Excuse us if we seem demanding, but we're of the opinion that if you ask what [unknown thing A] is, you deserve to know what it is. You don't necessarily need to know every little detail about it, but we're pretty sure that defining [unknown thing A] in 19 words and then going into tangential details for another 359 words doesn't cut it. That, unfortunately, is precisely what Alicia Bodine tried to do for WiseGEEK in her theHealthBoard.com post, "What is Contrast Dye?"

Bodine might well have used the work of fellow WiseGEEkian Felicia Dye as a model for her post, since that one is only slightly more useful than Alicia's attempt. As it is, Bodine managed to spit out a very basic definition by telling her readers right up front that,

"Contrast dye is a pharmaceutical liquid used in computed axial tomography (CAT) scans, magnetic resonance imaging (MRI), and X-rays. It is needed to make any injuries or diseases visible to the physicians ordering the test."

Yes, Alicia, do go on... but that's pretty much where she stops describing contrast dyes. In reality, she ends up conflating contrast dye with all forms of contrast media, going into more detail than might be necessary to explain both the oral and rectal administration of barium sulfate for gastrointestinal diagnostic tests. As part of her discussion, Alicia informs us that,

"A patient may have to go to the bathroom a few times after the test is finished to fully get rid of the dye."

Gee, thanks for that image: wonder if it works for arteriograms? Alicia also takes the page space to inform us (finally) that,

"Patients should be asked to sign a form stating that they understand the potential dangers associated with consuming this material."

What Alicia never manages to spit out is how contrast dyes manage to "make any injuries or diseases visible" – not a single word. So here's how contrast media work: some are radiopaque, meaning that they absorb X-rays better than flesh and bone, showing up as white or very light in radiographic images, including CAT scans and x-rays. That contrast can reveal abnormalities in the organ or bone being studied.
For MRIs, the contrast dye contains gadolinium, a magnetic metal. Again, bright spots in the images contrast with the duller images of non-metallic organic material. Other scans in nuclear medicine use radioactive elements in the contrast medium.

Bodine's version is light on facts and heavy on padding, which is one of the chief criteria we use in nominating a post for the singular honor of a Dumbass of the Day award. Congratulations, Alicia...

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