MRI-enhancing agents need warning: FDA

WASHINGTON (Reuters) - Contrast agents used to make magnetic resonance imaging, or MRI, scans easier to see should carry new, strong warnings, the U.S. Food and Drug Administration said on Wednesday.

The warning -- a "black box" -- would alert patients with certain kidney and liver conditions that they are at risk for a potentially fatal skin disease called nephrogenic systemic fibrosis, the agency said in a statement.

Such gadolinium-based imaging agents are made by Bayer AG's Bayer Schering Pharma, General Electric Co's GE Healthcare, Tyco International Ltd's Mallinckrodt unit, and Bracco Diagnostics Inc., the FDA said.

Agency officials first alerted doctors to the potential risk in June 2006 and again in December 2006, following reports that patients who received the injectable agents developed nephrogenic systemic fibrosis, or NSF.

The condition triggers thickening of the skin, organs and other tissues that makes it difficult to move and can lead to broken bones, although the exact cause is unclear. There is no effective treatment.

The new warning would alert patients with severe kidney insufficiency, as well as those with liver transplants or chronic liver disease experiencing kidney insufficiency, that they are at risk for NSF.

The FDA said the reports did not always mention a specific product, but that GE Healthcare's Omniscan, Bayer's Magnevist and Mallinckrodt's OptiMARK were the top three reported.

Patients should be screened for kidney problems before use of such agents, the agency said, adding that the recommended dose should not be exceeded. Doctors should also make sure that a given dose has been eliminated from the body before giving the agent again.