Non-ionic
Non-ionic contrast media are contrast media that do not dissociate when solved in water. The number of particles in solution per iodine atom is therefore lower than for ionic contrast media. Non-ionic monomeric contrast media consist of one benzene ring with 3 iodine atoms ("Ratio 3 "). Their osmolalities are about half that of ionic monomeric contrast media, or 2.5-3 times the osmolality of blood at the highest available concentrations. Non-ionic dimeric contrast media have two linked iodinated benzene rings. These molecules have 6 iodine atoms per particle ("Ratio 6 "). Non-ionic contrast media are more physiological than the older, ionic ones, resulting in examinations hampered by fewer and milder adverse reactions and discomfort.
GE Healthcare Glossary