Harvard Health Letter

By the way, doctor: Are MRI contrast agents harmful?

Q. Do the contrast agents used with MRI scans have side effects? I have had several MRIs and am wondering if there's reason to be worried.

A. Not all magnetic resonance imaging (MRI) scans require contrast agents, but a contrast agent is sometimes used to show blood vessels or the amount of blood flowing to a particular structure.

Most of the contrast agents for MRI scans contain a metal called gadolinium. The gadolinium is attached to other chemicals to keep it from causing any harm. If your kidneys are healthy, you'll excrete the contrast agent before that complex has a chance to break down. But if your kidneys aren't working well, it may break down before it is excreted, so unbound gadolinium persists in the body. When that occurs, it may lead to a complication called nephrogenic systemic fibrosis (NSF), which can thicken the skin and connective tissues throughout the body. While there are reports of NSF as far back as 1997, the association with gadolinium was first identified in Denmark in 2006. Since then, NSF has been recognized as an extremely rare but potentially debilitating complication of giving gadolinium-based contrast agents to patients with poor kidney function. As a result, it's now routine to screen patients for kidney function before giving contrast for an MRI scan. The screening isn't complicated: a simple blood test of creatinine levels is all that's needed. Some MRI centers can measure creatinine on the spot, so the blood sample doesn't need to be sent to an outside lab.

To continue reading this article, you must login.
  • Research health conditions
  • Check your symptoms
  • Prepare for a doctor's visit or test
  • Find the best treatments and procedures for you
  • Explore options for better nutrition and exercise
Learn more about the many benefits and features of joining Harvard Health Online »