Contrast agents in X-ray computed tomography and its applications in oncology.

Intravascular iodinated contrast agents are required for a large proportion of computed tomography (CT) studies. Contrast media are indispensable to more clearly differentiate anatomic structures and to detect and characterize abnormalities. Depending on the indication up to 200 ml of these agents are injected during CT. Despite these large amounts adverse effects are rare and have further decreased with the introduction of non-ionic substances. However, it took 10 to 20 years until these non-ionic agents replaced the older ionic agents in clinical practice. In recent years no new substance has been brought to the market. The introduction of rapid scanning using multislice CT technology, however, has led to the development of more sophisticated contrast injection techniques. Current research focuses on optimizing contrast application techniques and on further evaluating the safety profiles of the various substances. The amount of contrast enhancement obtained in individual patients for instance depends on the contrast agent characteristics, such as iodine concentration, and the parameters of the contrast injection protocol, such as iodine flux and iodine dose. Meanwhile, contrast agent characteristics such as osmolality and viscosity play a role in the safety profile of an agent. This paper provides a current overview of CT contrast media, CT contrast dynamics, and CT contrast applications with a special focus on oncological imaging.