Medical Edge Newspaper Column

Contrast Agents Help Create Clear Picture in Certain Types of MRI Exams

February 17, 2012
Dear Mayo Clinic:
I have had an acoustic neuroma for ten years. When it was first diagnosed, I had fractionated stereotactic radiosurgery. Since then, I have had 18 MRIs with gadolinium injections. Have there been studies done on the effect of these injections? Does the number of injections over one's lifetime increase the risk of harmful effects?

Answer:
If your kidney function is normal, having multiple magnetic resonance imaging (MRI) exams with gadolinium does not pose a known health risk. In people with abnormal kidney function, however, gadolinium may not be safe.

Gadolinium is a substance in MRI contrast agents that is useful for creating a clear picture of the body in certain types of MRI examinations. Not all MRIs require a contrast agent. When needed, contrast agents are injected through an intravenous catheter in the hand or arm during the exam.

Gadolinium-based contrast agents, or GBCAs, are manufactured through a process that makes the products safer for humans. If you have an MRI with one of these agents, your body eliminates most of it through your kidneys, and usually there are no lasting effects from GBCAs.

Patients who receive GBCAs may experience an allergic reaction during or shortly after an MRI examination. Reactions to GBCAs are less common than reactions to iodinated contrast material that is used for some computed tomography (CT) scans. Allergic reactions to GBCAs range in severity from minor to serious. Examples of allergic reactions include rash, itching, hives and facial swelling. Serious reactions, such as bronchospasm (trouble breathing), are rare. Each time you are injected with a GBCA, an allergic reaction is possible. Beyond that, if you have normal kidney function, receiving multiple doses of gadolinium over the years does not appear to pose additional known risks.

However, if you have abnormal kidney function — especially, severe kidney failure — your situation is different. In people with kidney disease, GBCAs have been associated with the development of a rare but serious disease called nephrogenic systemic fibrosis (NSF). This debilitating disease triggers thickening of the skin, internal organs and other tissues. Currently, NSF has no effective treatment and can be life-threatening.

In those who receive GBCAs, NSF appears to develop in people who have significantly abnormal kidney function, including those receiving kidney dialysis. If you have a history of kidney problems, tell your doctor and the MRI technologist who will be performing your exam. Medical centers that use GBCAs should have a policy regarding who can safely receive them, based on an evaluation of the patient's kidney function.

If you cannot receive GBCAs due to abnormal kidney function or prior severe allergic reaction, your doctor may select a different imaging test to evaluate your medical condition. It is safe to have an MRI scan performed without GBCAs if you have abnormal kidney function.

In your situation, even if your kidney function is fine, you may be able to opt out of receiving GBCAs for future MRI exams. Typically, acoustic neuromas can be easily viewed on another type of MRI sequence — known as high-resolution heavily T2 weighted images — which could likely be used to monitor your acoustic neuroma. These images do not require a GBCA.

— Geoffrey Fletcher, M.D., Radiology, Mayo Clinic, Scottsdale, Ariz.