Have you ever had an MRI to diagnose osteoarthritis of the hip or check for cancer or an aneurysm? MRI or magnetic resonance imaging is considered much safer than CT scans that require ionizing radiation. It is estimated that 20 million MRIs are conducted in the U.S. each year.
One aspect of these scans is now under scrutiny, however. About one third of MRIs involve injections of a contrast agent to make the resulting image clearer. Some contrast agents contain gadolinium, a rare earth chemical element. An investigative report from ProPublica reveals that some products, Omniscan and Magnevist, are associated with gadolinium residues in brain tissue after imaging.
The first problem noted with gadolinium was kidney toxicity. Nephrogenic systemic fibrosis is as bad as it sounds. In some cases it can be life threatening, and in 2007 the FDA put a black box warning on these contrast agents for patients with kidney impairment.
Unexpected Hazards of MRIs
The fact that traces of gadolinium remain in the brain is a relatively recent finding. Doctors are still uncertain about whether this has clinical significance. Some patients have reported cognitive impairment following MRI. An editorial in the journal Radiology calls for re-evaluation of previous assumptions of safety of the gadolinium compounds in such contrast agents. When radiologists are nervous, it makes us worry too.
The next time you need an MRI, ask your doctor if contrast is essential and what kind they are using. Perhaps that way you can minimize your exposure to gadolinium and the uncertain hazards of MRIs.
