FDA Approves First Imaging Agent To Enhance Scans Of Blood Flow
The U.S. Food and Drug Administration today approved Vasovist Injection (gadofosveset trisodium), the first contrast imaging agent for use in patients undergoing magnetic resonance angiography, or MRA, a minimally invasive test for examining blood vessels.
Although MRA can be performed without the use of a contrast imaging agent, Vasovist administration provides a clearer image in patients who are suspected of having blockages or other problems with the blood vessels in their abdomen or limbs. The MRA is performed using magnetic resonance imaging (MRI), which relies on magnetic fields to create highly detailed images of the inside the body.
"This MRA contrast imaging agent provides clinicians with a much clearer scan of blood vessels, compared to MRA without contrast, even in vessels that are difficult to scan because they twist and turn in the body," said John Jenkins, M.D., director, Office of New Drugs, Center for Drug Evaluation and Research, FDA.
When blood vessels are scanned using MRA without any contrast, radiologists are unable to interpret the images about 10 percent to 30 percent of the time. As a result, radiologists have typically used X-rays to detect blood vessel abnormalities. But this is a lengthy procedure and requires sticking a needle into an artery to inject the X-ray dye, a procedure that may result in injury to vessel walls, blood clots, allergic reactions and potential kidney damage. Vasovist is injected into a peripheral vein and no artery is punctured, thus the potential risks are fewer.
The active substance in Vasovist is gadolinium, a rare earth metal element that is detected by MRI scanners. When injected, gadoliunium interacts with water molecules in the body, giving a stronger signal and, in turn, a better picture.
The safety and efficacy of Vasovist was established in two clinical studies of patients with known or suspected aortoiliac disease --- plaque buildup in the arteries going to the legs. In the studies, patients underwent MRA with and without Vasovist and their scans were compared to standard X-ray pictures using contrast. MRA with Vasovist detected more arterial disease than MRA performed without Vasovist and the pictures were of improved technical quality.
The primary safety risks for Vasovist are allergic reactions and n ephrogenic systemic fibrosis, a rare syndrome that involves the thickening of the skin, joints, eyes and internal organs. The FDA issued a warning about this syndrome in May 2007 and information about it is included in a boxed warning for all drugs containing gadolinium, including Vasovist.