Nephrogenic systemic fibrosis: Possible mechanisms and imaging management strategies

Abstract

It is important to maintain a sense of perspective and bear in mind both that gadolinium chelates are among the safest agents ever devised and that even in high-risk patients the likelihood of developing NSF appears to be less than 5%. Nevertheless, NSF is a very serious condition and sensible precautions must be taken by everyone using gadolinium chelates. The pathophysiology of NSF has not been elaborated but the circumstantial evidence strongly suggests a key role for gadolinium liberated from the chelate in a situation of in vivo competition with other ions, prolonged residence time in the body in ESRF, and a low pH; if there is coexisting hepatic impairment, another route for excretion of the chelate is lost. The chemistry of such a competitive liberation of Gd 3+ is well understood and the relative stabilities of the various chelates are broadly predictable from an examination of their structures. Cyclic chelates are more stable than linear/acyclic chelates, whatever measure of stability is used, and some linear/acyclic chelates are predictably less stable than others. As discussed, such theoretical considerations are broadly borne out by observation in clinical practice. Current knowledge is incomplete and the course of avoiding any of the Gd chelates in patients with GFR lower than 30 mL/minute/1.73 m2, as recommended by various authorities, seems the most sensible one to adopt. If the examination must be done with contrast enhancement, a cyclic complex should be used. The problem presented by the patient whose renal function is not known may, this author believes, be tackled by taking a careful history from each and every patient for whom a recent renal function measurement is not available. Any cases of NSF encountered should, of course, be thoroughly documented and reported to the appropriate national authority and to the NSF database (26). © 2008 Wiley-Liss, Inc.