- magnetic resonance imaging
- Magnetic resonance imaging: advantages and disadvantages
As bulky as the name is the device - a man-sized magnet with a narrow, round opening, through which the patient is pushed. Archaic sounds the noise that can be endured only with headphones. But the MRI provides excellent cross-sectional images of the internal organs, without any radiation exposure.
Development of magnetic resonance tomography
The principle of magnetic resonance has been known to scientists since the 1950s. First, it served to visualize the chemical structure of complex molecules. The chemist Lauterbur and the physicist Mansfield had the groundbreaking idea to use the phenomenon for insights into the human body; In 2003, they received the Nobel Prize for Medicine. The medical diagnostic devices that have been in existence since the early 1980s have undergone huge development over the past thirty years.
Now there are whole body scanners that scan the body from head to toe in 12 minutes. Whether cartilage damage after injury or osteoarthritis, the extent of tissue damage after a heart attack or stroke or the early diagnosis of diseases such as multiple sclerosis or Alzheimer's disease - the magnetic resonance imaging (MRI) reliably provides colored "maps" of the examined tissue.
How does Magnetic Resonance Imaging work?
Each atomic nucleus has an intrinsic angular momentum (nuclear spin), through which a small electromagnetic field is generated, which normally points randomly at random. If a stronger magnetic field is applied from outside, these small fields all align the same. Therefore, the core of the MRI device is a giant magnet whose field is on average 10,000 to 30,000 times larger than the earth's magnetic field.
Since the human body consists predominantly of water, hydrogen atoms are particularly well suited for measurement. As soon as their cores are synchronized by the magnetic field, radio waves sent into the fabric, which bounce on the cores and thus make them falter - the Resonance effect. This gives the cores energy - they are stimulated.
This is how the sectional images are created
When the magnetic field is switched off, the cores return to their original position and release this energy in the form of electromagnetic waves. These signals are registered by highly sensitive receivers from different directions and by computer in sectional images (Tomograms) implemented.
Since the different types of tissue in the body contain different amounts of water (for example fatty tissue a lot, bone a little), they give off more or fewer signals and thus appear differently, namely lighter or darker.
From the procedures described, the names for the procedure are derived - magnetic resonance or magnetic resonance imaging (MRI). The investigation itself is very loud; the examination rooms are for the protection of the personnel soundproofed. In order for the patient to be noticeable in the tube, he receives one shortly before the start of the examination Bell. During the examination preparation he can talk to the staff by means of an intercom.