The safety of gadolinium-based contrast agents (GBCAs) used to enhance MRI images has, in recent years, become one of the biggest concerns in radiology. GBCAs contain gadolinium, a heavy metal. Patients and radiologist began to question the safety of GBCA when a study came out in 2014 showing that gadolinium is retained in various organs.
The American College of Radiology called gadolinium contrast agents “effective” and “safe” for MRIs, but also pointed out that the agents may leave deposits in the bone, brain, and other organs. Similarly, in a safety announcement issued in December 2017, the Food and Drug Administration (FDA) acknowledged that gadolinium deposits can be retained in the brain, for months to years after the patients receive the injection. However, there’s no substantial evidence showing that the retention of gadolinium deposits is harmful.
Individuals at higher risk may include children, pregnant women, patients who need multiple lifetime doses, and those with inflammatory conditions. Nephrogenic systemic fibrosis is an established adverse impact related to the retention of gadolinium. It affects a small group of patients with poor renal function. However, the FDA has received reports that highlight adverse events in a number of patients with normal renal function, but an association between gadolinium retention and the adverse effects has not yet been established.
The FDA requires several actions to alert patients and healthcare professionals about possible retention of gadolinium after an MRI:
- A new Patient Medication Guide providing educational information on GBCAs
- Every first-time outpatient must be asked to read the guide before they are injected with a GBCA or when the information is substantially changed
- Manufacturers of GBCAs must conduct further research to assess the safety of the agents
The FDA also recommended an update on the labeling for these agents so they warn health practitioners of the possibility of gadolinium retention in various organs. Healthcare practitioners are required to consider retention characteristics of each agent and minimize repeated GBCA MRI scans, especially those that are closely spaced. However, according to the FDA, restricting the use of gadolinium contract is not warranted as of yet and necessary scans should not be avoided or deferred.
GBCAs are injected into a vein to improve visualization of tissues, blood vessels, and internal organs, making it possible to examine the body for problems such as infections, bleeding, or cancer. GBCAs are mostly extracted from the body via the kidneys.