Contrast media can be used in various imaging procedures, such as X-ray, CT or MRI. They serve to better recognize possible disease processes and can make even small, pathological changes in our body visible. The group of contrast media includes various drugs that are optimized for the respective examination.
In computer tomography (CT), for example, this is a contrast medium containing iodine. In rare cases, severe allergic reactions and side effects can occur, especially with this type of contrast medium. As the kidney and thyroid gland are particularly at risk, the associated laboratory values are usually checked before the contrast medium is administered. Due to the ever-increasing compatibility, the majority of CT and MRI examinations today are carried out using contrast media.
Why contrast medium?
As the name suggests, contrast agents enhance the contrast and differentiation of different structures and tissues. Depending on the problem, individual structures can be better distinguished from one another. In addition, it is possible to visualize even extremely small disease processes.
Diseases, for example, can thus be detected at an early stage and treated in time. Contrast media are therefore not among the “classic” drugs that bring relief or improvement of symptoms. Instead, they have gained enormous diagnostic importance!
As a rule, contrast media enter our blood system directly via a venous access. For this purpose, a small intravenous cannula is placed in an easily accessible vein, usually in the crook of your arm. In order to display abdominal organs particularly well, it may be necessary to drink the contrast medium.
Different contrast media
Basically, all contrast media have the task of altering or amplifying the signals sent during the examination (e.g. radiation during X-rays). Logically, their properties therefore depend on the examination method used:
- MRI: During magnetic resonance imaging, the smallest particles of our body (hydrogen nuclei) are aligned by a magnetic field. The resulting alternating phases of oscillation and relaxation of the particles can be detected and displayed by the sensitive MRI equipment, so that very detailed sectional images can be produced.
In order to produce even better and more informative images, gadolinum-containing contrast medium can be used. It belongs to the so-called “paramagnetic” substances and influences the relaxation properties of our tissue. Certain structures in the images appear brighter or more distinct.
For some questions concerning the liver (e.g. tumors), special iron-containing contrast media are available: Put simply, only healthy liver cells are capable of metabolising iron. This makes it relatively easy to identify diseased liver cells on the MRI image. The gas helium, which is harmless to humans, is used for an MRI of the lungs.