ABSTRACT
Iodinated contrast agents used for radiographic procedures are
unique pharmaceuticals. They are available as highly concentrated
solutions that are administered at high doses; this is possible
because of their high safety profile and special physicochemical
properties (high hydrophilicity and inertness). The currently used
iodinated contrast agents can be divided into two classes based on
their chemical structure.Monomeric agents are composed of a single
triiodinated benzene ring, whereas dimeric agents consist of two
covalently linked triiodinated benzene rings [1]. The passage from
ionic to neutral systems has markedly improved their safety profile,
making adverse reaction to their administration rare events [2].
Besides their capability to induce contrast in computed tomography
(CT) images, owing to the presence of high X-ray adsorbance iodine
atoms, the concomitant presence of amide groups has driven an
interest in their exploitation as magnetic resonance imaging (MRI)-
chemical exchange saturation transfer (CEST) agents. In seeking
routes to accelerate the entry of CEST agents into clinical practice,
it has been rather straightforward to consider chemicals already
approved for human use and potentially able to generate CEST
contrast. On this basis, a systematic study of currently used X-
ray contrast agents containing mobile protons (e.g., Iopamidol-
Isovue R© Bracco Imaging SpA, Italy; Iopromide-Ultravist R© BayerSchering AG, Germany; and Iobitridol-Xenetix R© Guerbert, France) has been undertaken. The in vivo results obtained so far appear very
encouraging for clinical translation of these CEST agents.
