Why choice of contrast medium matters

Abstract

Three generations of iodinized contrast media (CM) are available for use in visualization of X-ray procedures. The three types of CM are all primarily based on a tri-iodinated benzene ring structure but differ in the structure of the attached side chains. First-generation CM have an ionizing carboxyl group, meaning they dissociate into two particles in solution. Consequently, these CM have a high osmolality that has been found to result in toxic effects such as pain and heat sensation on injection and a significant risk of CM-induced nephropathy (CIN)—an important adverse event associated with CM use. Low-osmolar CM (LOCM) were developed to overcome these toxic effects and are indeed better tolerated than high-osmolar CM (HOCM). In particular, LOCM have been shown to carry a lower risk of CIN, especially in high-risk patients. However, renal failure is still one of the most severe reported adverse events associated with LOCM. Therefore, a third generation of CM has been developed that is iso-osmolar with plasma offering potential benefits with regards to tolerability compared to LOCM. Two studies in high-risk patients have shown that iodixanol is associated with a lesser effect on renal function than the LOCM iohexol. Thus, clinical data have shown that an iso-osmolar CM should be considered in patients at high risk for CIN undergoing CM-enhanced procedures.