By: Dan Sperling, MD

Many MRI scans involve the use of a contrast agent to enhance the appearance of blood vessels or other key structures. This increases the clarity and accuracy of the information being sought during the scan. The most commonly used agents for this purpose are based in a silvery white chemical element called gadolinium. Because it would be toxic if it freely circulated in the body, its atoms are bonded with molecules that “cage” it so it’s harmless. After the scan, the circulatory system carries the agent to the kidneys, which then flush it from the body.

Gadolinium-based contrast agents (GBCA) have long been in use and considered safe for adults. However, patients whose kidneys are not functioning properly must avoid having this agent because damaged or diseased kidneys will not properly excrete GBCAs from the body.

Therefore, before scheduling a patient for an MRI scan in which contrast will be involved, it is absolutely essential that the patient have a simple blood test that measures renal (kidney) function. Without this routine test, the individual safety of the patient is placed at risk.

A recently released report of a British survey of radiology centers revealed a rather alarming situation: despite existing international guidelines on contrast agent safety, the application of testing renal function was inconsistent.[i] The sites were invited to voluntarily complete an online survey, and about 40% responded. Of those who completed the questionnaire, 82.3% indicated they had a safety policy in place. However, according to one news story, “More than 41% (28 sites) checked blood test results for all patients, whereas 31 sites (45.6%) only checked those with known renal dysfunction or identified as high risk for renal impairment.” In other words, almost a third of the centers did not routinely screen each and every patient for kidney function.

This in itself is worrisome, but there is an additional concern that affects even those with healthy kidneys. Since 2014, there have been published studies in which “deposits” of gadolinium were found in the brain following brain MRI using contrast. Although this may not be common, no one knows how long the deposits remain there, or what they might do.

Today, there are a few gadolinium-based agents that are formulated differently from standard GBCAs. Two of them, Dotarem and Gadavist, have been tested on patients who need repeat MRI scans; there is no evidence that deposits are left behind. Dotarem, which was approved by the FDA in 2013, is so safe that even children who require brain scans with contrast show no evidence of residue in brain tissue or elsewhere. To date, Dotarem appears safe even when kidney function is mildly compromised, but the safest principle is to avoid contrast use if there is any doubt. There are ways to obtain the needed information without it, especially with today’s powerful, advanced magnets.

At our Center, patient safety is always primary. After reviewing the evidence, we were a leader in our choice of Dotarem as our contrast agent. Like other GBCAs, it comes with precautions. However, its increased safety allows use with a wider range of patients. If it is not indicated for a patient, our state-of-the-art magnet allows imaging sequences that provide the needed detection and diagnostic information. We strive for excellence in both patient care and in the image-based information we provide to patients and their doctors.

[i] http://www.auntminnieeurope.com/index.aspx?sec=sup&sub=mri&pag=dis&ItemID=613222