term usually reserved for iodinated X-ray contrast media with an osmolality substantially lower than the traditional high-osmolar ionic, monomeric contrast media at the same iodine concentration. Low-osmolar contrast media may be grouped as nonionic monomers, ionic monoacidic dimers, and nonionic dimers (see X ray contrast media). The first two groups have a higher osmolality than plasma in clinical concentrations; only the nonionic dimers are available as isotonic or nearly isotonic solutions.
HJS
