A dye used in millions of magnetic resonance imaging (MRI) scans worldwide can be poison for people with serious kidney problems and cause a debilitating, incurable and sometimes fatal disease called neophrogenic systemic fibrosis (NSF).
Dyes based on gadolinium — the magnetic ion blamed for the condition — are safe for most people, said David Seidenwurm, a neuroradiologist with Radiological Associates of Sacramento. But for people with severe kidney problems, the ion can poison the patient by causing collagen to build up in tissues.
The U.S. Food and Drug Administration asked manufacturers in May to include a so-called black-box warning on gadolinium-based products, saying patients with kidney problems could develop NSF after a single exposure. In addition to severe thickening of the skin, leading to immobility, the disease is also known to affect the liver, the lungs and the heart.
The specific cause of NSF is not yet known, but researchers at Yale University reported that in more than 95 percent of the cases they had surveyed, patients were exposed to a gadolinium-based dye two to three months before the onset of the disease.
Shawn E. Cowper, a dermatologic pathologist at Yale who first identified the condition with Philip LeBoit of the University of California-San Francisco, said as many as 1 in 20 kidney patients could be at risk of contracting NSF after undergoing an MRI using gadolinium.
Gadolinium-based dyes latch into specific tissue types in the body, making them easy to contrast from other tissues on an MRI. The tests can be administered without a contrasting agent, but they are considered to be significantly less useful.
Complicating the problem is that gadolinium is the only contrasting agent approved for use in most MRIs. Two others, Feridex I.V. and Teslascan, are limited to use only in examinations of specific liver problems.
NSF has been confirmed in children and the elderly, but it tends to affect the middle-aged most commonly, according to the International Center for Nephrogenic Fibrosing Dermopathy Research. It affects men and women equally.
Source: Xinhua/agencies
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