Medical imaging and chemistry

Diagnostic imaging frequently requires the use of agents that do not show an obvious role to patients. Nevertheless, these products fall definitely in the drug category and therefore are bound to the same development constraints, although no therapeutic effects are expected. This article attempts to explain the physical background of the most common imaging technologies as well as the mechanisms of action of the administered products. With these substances it is now possible to get morphological information with techniques based on X-rays, magnetic resonance or ultrasound, but also to obtain information on the functions of organs or cells by using radiolabeled molecules. Progresses, perspectives and limits of these technologies are described through several concrete examples. This overview demonstrates also that imaging participates strongly to the development of medicine. Diagnostics benefit simultaneously from technology improvements and new pharmaceuticals.