New MRI contrast may be safer than gadolinium-based agents

A team from Massachusetts General Hospital (MGH) has created a novel contrast agent for MRI exams that may be safer than those requiring gadolinium.

The new agent is manganese-based (Mn-PyC3A) and produces tumor contrast enhancement similarly to that seen when using “state of the art” gadolinium-based contrast agents (GBCAs), according to a statement from MGH. Manganese clears more quickly and thoroughly from the body than GBCAs, the team noted, meaning the new agent may be a safer choice for patients.

Study author Peter Caravan, PhD, described the novel agent in new research published in Investigative Radiology. He noted one of its key features is using manganese that is “tightly bound” to a chelator to prevent the element from negatively interacting with cells or proteins; this also allows it to be expelled from the body after an exam.

“Without a chelator of sufficient strength, the manganese will be taken up by the liver and remain in the body,” Caravan, co-director of MGH’s Institute for Innovation in Imaging, said in the release.

In the study, the team compared their contrast agent against two state of the art GBCAs—Gd-DOTA and Gd-EOB-DTPA—to detect tumors in mouse models of breast cancer and metastatic liver cancer. Overall, Mn-PyC3A provided comparable tumor contrast enhancement and was more completely eliminated from a rat model than the other two GBCAs.

The first GBCA was approved by the FDA in 1988, but there have been numerous studies confirming gadolinium retention in the brain and other organs connected to an increased exposure to GBCAs. These concerns caused the European Medicines Agency to take several GBCAs off the market in Europe. And while senior author Eric M. Gale, PhD, assistant in Biomedical Engineering at MGH, said there is no consensus recommendation against GBCAs, there is still a demand for safer options.

"No confirmed side-effects have yet been irrefutably linked to the long-term presence of gadolinium in the body,” Gale said. “But, since some people are repeatedly exposed to GBCAs, doctors want to be cautious.”