What types of contrast agents are available for intravascular use?
Iodinated contrast agents are used in all studies where x-rays are utilized, such as CT, intravenous urography (IVU), and all fluoroscopic studies. These can be broadly classified based on osmolality (high, low, or iso-), ionicity (ionic or nonionic), and the number of benzene rings in the chemical structure (monomeric or dimeric). Nonionic contrast agents are associated with less discomfort during intravascular administration and fewer adverse reactions compared to ionic contrast agents. Therefore, nonionic low osmolal or iso-osmolal contrast agents are almost exclusively used in current clinical practice for intravascular injections, particularly in developed countries.
Gadolinium-based contrast agents are used in MRI studies and can be classified based on ionicity (ionic or nonionic), the chelating ligand (macrocyclic or linear), and the pharmacokinetics (extracellular or organ specific). Ionic and nonionic agents have relatively little or no difference in acute reactions and discomfort.
There are other types of intravascular contrast agents, such as iron oxide–based contrast agents that are used in MRI studies and microbubble contrast agents that are used in ultrasonography (US) studies