MRI and Kidney patients: The hard facts on a rare Disease

Rockville, MDA medical procedure that we've come to respect, and even revere for its capacity to reveal physiological abnormalities in the body, could pose a serious health risk for patients with kidney damage or renal failure. At issue are contrasting agents often used in association with the MRI, and MRA.

Magnetic Resonance Imaging picks up where the X-ray left off, providing detailed, full-colour images of soft body tissue, and the vascular system. While no radiation is used for either imaging protocol, a chemical dye is often injected into the patient to aid in the imaging process.

However, it was revealed in 2006 that there is a concern surrounding gadolinium-based contrasting agents (GBCA), and a suspected link with Nephrogenic Systemic Fibrosis/Nephrogenic Fibrosing Dermopathy (NSF/NFD), a potentially life-threatening fibrosis that affects the skin and other areas of the body. This fibrosis, or hardening and thickening of skin and other vital tissues, can reduce mobility in the short term. The condition is progressive, and potentially fatal.

Patients with kidney disease are particularly at risk, and there is no known cure.

NSF/NFD first appeared in 1997, and began to show up in medical literature three years later. Beyond the fact that NSF/NFD seemed to be most prevalent in patients with advanced renal failure and kidney damage, there was little known about the disease until 2006.

That's when a Danish study surfaced that appears to point the finger at one of the five contrasting agents approved for MRI by the U.S. Food and Drug Administration (FDA) for use in the United States.

Of those five, Omniscan - and the only contrasting agent licensed in those countries that were the focus of the Danish study, has come under scrutiny. The FDA is currently investigating all five of its approved contrasting agents including Omniscan, OptiMARK, Magnevist, ProHance, and MultiHance, for any potential link to the rare, but devastating NSF/NFD disease.

At the heart of the issue is gadolinium, which is a paramagnetic metal ion and the basis for all of the approved injectable contrasting agents used in magnetic imaging procedures. The contrasting agent, or dye, effectively highlights the area of the body focused for the imaging.

Following the procedure, the expectation has always been that the kidneys would dispense with the gadolinium, ridding it from the body.

However, patients with weak or otherwise compromised renal systems and other forms of kidney damage face the possibility that the gadolinium can remain in the body for a lot longer - if not permanently - as their weak kidneys cannot adequately flush the gadolinium from their systems.

The Danish study findings were published in a report by Brobner et al in Nephrology, Dialysis and Transplantation in April of last year, and further articulated in a release by the Danish Medicines Agency (DMA) on May 29th 2006. The study revealed that renal failure patients appeared to have an issue with retention of gadolinium. Concern only increased once it was revealed that all patients in the study received a gadolinium-enhanced MRA procedure anywhere from a few weeks, to a few months prior to developing NSF/NFD

It should be noted that the five contrasting agents approved for use in the United States by the FDA, are approved only for the MRI procedure, and not for MRA. The latter requires a higher dose of gadolinium, up to three times the usual level for MRI. While gadolinium-based contrasting agents are used for some MRA procedures, there are none that carry the approval of the FDA.

The U.S. Food and Drug Administration has asked the manufacturers of the five GBCA contrast agents to include black box warnings concerning the risks for developing nephrogenic systemic fibrosis, and to expand the language in product literature.