How Do MRI Contrast Agents Affect The Body?

When you get an MRI, you are often given something called a contrast agent. A contrast agent is a compound that helps increase the clarity of the MRI image, and it is either injected or taken orally before you undergo the imaging procedure.

When you have a condition that requires you to get multiple MRIs, you may be taking multiple small doses of a contrast agent, and we do not have a lot of information about how these repeated doses affect the body. A new study from NYSCF – Robertson Investigator Winrich Freiwald, PhD, Assistant Professor at The Rockefeller University, examined this issue for a type of contrast agent called ultra-small paramagnetic iron oxide (USPIO).

Dr. Freiwald and colleagues administered a small amount of a USPIO compound to rats once a day for four weeks. The researchers found that at the end of the four weeks, iron began to accumulate in the ventricles (cavities filled with cerebrospinal fluid) of the rat’s brain at an equal or higher amount than would typically reside in those areas.

The study also showed that repeated dosing caused vacuolation (the formation of small holes) in the midbrain, a symptom also seen in mice lacking iron regulatory proteins. Excess USPIO then tended deposit in the liver or spleen.

Future research will address how drugs that break down iron may be able to correct for the iron buildup observed in this study. The researchers also suggest that people receiving frequent MRIs should be monitored using a contrast technique like QSM or susceptibility-weighted imaging, which help identify and quantify biomarkers such as iron.

For more information, check out the paper in Comparative Medicine.