The U.S. Food and Drug Administration’s investigation into MRI contrast agents containing gadolinium, launched almost two years ago, has turned up zero evidence implicating these heavy-metal substances in any harms to the human brain.The off-the-hook signal even goes for gadolinium-based contrast agents (GBCAs) associated with higher retention in organs.The agency presented its findings in a safety announcement released May 22. It reads, in part:“We evaluated scientific publications and adverse event reports submitted to FDA. Some human and animal studies looked at GBCA use over periods longer than a year. These publications and reports show that gadolinium is retained in organs such as the brain, bones, and skin. The publications show that linear GBCAs retain more gadolinium in the brain than macrocyclic GBCAs. However, our review did not identify adverse health effects related to this brain retention.” FDA says it will not restrict the use of GBCAs but will continue to assess the safety of GBCAs and hold a public meeting on the subject at some point in the future.To read the full May 22 announcement, click here (PDF).