Liver MR protocols address fibrosis threat

The apparent link between nephrogenic systemic fibrosis and certain gadolinium-containing MR contrast media has led to a tightening of procedures in radiology departments worldwide. Steps have been implemented to identify those patients who are most at risk of developing the debilitating condition, which leads to sclerodema-like skin thickening and discoloration and fibrosis of vital internal organs. A proportion of patients who contract NSF will die from the condition.

Radiologists dealing with referrals from urology and hepatology departments have undoubtedly been affected the most. To date, NSF has been observed only in patients with impaired kidney function. This category may include patients with advanced chronic liver disease or those who have acute liver failure.

Those at highest risk, according to European Society of Urological Radiology (ESUR) guidelines, are patients with a glomerular filtration rate (GFR) of less than 30 mL/min, individuals on dialysis, and patients with reduced renal function who have undergone a liver transplant or are waiting for a donor organ. The ESUR recommends that the use of MR contrast in this group be weighed against the likely benefit of the imaging study.

These guidelines note that the dose of all gadolinium contrast agents should be kept as low as possible for diagnostic purposes and should never exceed 0.3 mmol/kg. Serum creatinine measurements, to gain an estimate of GFR, are cited as "mandatory" prior to administration of the linear chelates gadodiamide (Omniscan; GE), gadopentetate dimeglumine (Magnevist; Bayer Schering Pharma), and gado-versetamide (OptiMark; Mallin-ckrodt). The guidelines list these three agents as being contraindicated in patients at high risk for NSF.

The U.S. Food and Drug Administration has requested that boxed warnings outlining the possible risks of NSF be displayed on all gadolinium-containing agents available in the U.S. This applies to the linear chelate gado-benate dimeglumine (Multi-Hance; Bracco), the macrocyclic che-late gadoteridol (Pro-Hance; Bracco), and the recently approved gadoxetic acid (Eovist; Bayer Schering Pharma) as well as Omniscan, Magnevist, and OptiMark.

The situation poses a conundrum for radiologists. Patients with reduced renal function have traditionally been steered away from contrast-enhanced CT owing to the risk of nephropathy being induced by iodinated contrast agents. Now, it seems, contrast-enhanced MRI is not entirely risk-free, either.

Radiologists at the St. Orsola-Malpighi University Hospital in Bologna, Italy, are managing patients with renal insufficiency on a daily basis, said Prof. Rita Golfieri, the hospital's director of radiology. Contrast-enhanced MRI examinations may still be performed in some. Protocols are in place to identify those individuals who should not be given MR contrast.