Nowadays there are many ways of looking inside the human body. Imaging techniques such as x-rays and
computed tomography (CT) allow radiologists to visualize bones, organs and other tissues. There is also a diagnostic procedure that goes even deeper: magnetic resonance imaging (MRI). It can be used to create detailed images of the anatomy and function of the organs in the body.
Doctors have been using this method for over 25 years to produce two- and three-dimensional images of anatomical structures. It is estimated that some 500 million MRI scans have been performed worldwide in this time. A magnet as tall as an adult person generates images of high-contrast sections through the body. They show organs, blood vessels, nerves, even tiny tumors, in detail. Nowadays there are even whole-body techniques for imaging the body from top to toe in just twelve minutes. MRI has one major advantage over other imaging methods such as CT and x-rays: it doesn’t use ionizing radiation. “This process works with magnetic fields,” explains Dr. Matthias Voth from
Bayer HealthCare Pharmaceuticals. “The patient doesn’t feel a thing, yet it still produces detailed images.”
These are generated by a giant magnet. The magnetic field causes the nuclei of atoms to alter their state temporarily. In medical imaging it is only the nuclei of the hydrogen atoms in the body that are of interest. There are plenty of them because two-thirds of the human body is made up of water – a chemical composed of hydrogen and oxygen.
The scanner generates raw data from the signals it receives. A computer converts the data into a diagnostic image.
Soft tissues such as the heart and brain, connective tissue, as well as muscles and nerves are particularly well endowed with hydrogen atoms. Each tissue has a specific density and hence a different concentration of hydrogen atoms. And this is precisely what shows up on the MRI scan. Diseased and healthy tissue can be clearly distinguished from each other because they frequently have different hydrogen contents.
Radiologists often use products called
contrast agents to make details appear even more clearly on the MRI image. These products are used in one third of all MRI scans. The first contrast agent for magnetic resonance imaging came onto the market in 1988. Products from Bayer HealthCare Pharmaceuticals are still some of the most widely used contrast agents even today, and have helped to enhance over 100 million scans to date.
“MRI contrast agents provide radiologists with important additional information,” Voth explains. Extremely accurate images can be obtained of blood vessels, for example, and this is enormously helpful in enabling doctors to make the right diagnosis. Contrast-enhanced MRI is also very useful in the initial diagnosis of breast cancer. Today this imaging technique is helping experts to gain an ever greater understanding of the functioning of the brain, an organ that for a very long time was a closed book.