Synonym
- Magnetic Resonance Imaging
- Magnetic Resonance Imaging
- NMR
Definition
The term MRI (magnetic resonance imaging) refers to an imaging procedure that serves to depict the human body. Like computed tomography (CT), MRI belongs to the group of sectional imaging techniques. MRI is a diagnostic technique used to visualize internal organs and various tissue structures.
MRI works with magnetic fields and radio waves. The patient to be examined is not exposed to any X-rays during this imaging procedure. There are, however, some restrictions for the preparation of an MRI.
For this reason, for example, people who have an implanted pacemaker cannot be diagnosed with the help of an MRI. There is limited experience to date in assessing whether performing an MRI examination during pregnancy can be harmful to the unborn child. An MRI during pregnancy must always be carefully considered.
However, due to the absence of radiation harmful to the fetus, an MRI during pregnancy is possible under certain conditions. Today, it is assumed that, in contrast to the preparation of X-rays, MRI examinations during pregnancy pose no risk whatsoever from radiation. Nevertheless, before every MRI examination it should be checked whether it is really necessary to take sectional images using magnetic resonance imaging. This is especially true during the first third of the pregnancy.
Functionality of the MRT
The functioning of a magnetic resonance tomograph is based on the formation of a very strong magnetic field. This magnetic field can be used to align the atomic nuclei, especially the nuclei of hydrogen atoms. In the process, the atomic nuclei change from a low-energy state to a high-energy state.
The atomic nuclei excited by the magnetic field are then set into oscillation. The magnetic resonance tomograph (MRI) can switch off the magnetic field it generates at regular intervals. In this way, the previously excited atomic nuclei fall back into their low-energy ground state and release energy.
This energy can be recorded by the MRI and converted into sectional images. The production of such sectional images with the aid of a magnetic resonance tomograph can be useful for various reasons. One main reason for using this imaging technique is the targeted and differentiated imaging of all body tissues.
In contrast to conventional X-rays, the MRI is able to image non-bony structures, such as soft tissue, organs, joint cartilage, intervertebral discs or the brain. In addition, detailed images of the heart can now be produced. With the help of magnetic resonance imaging (MRI), even minor changes in the body, such as inflammatory processes or small growths, can be detected with pinpoint accuracy. Anatomical structures that only have a low water content, such as bones or the air-filled lung, cannot be optimally depicted with MRI, however. In this case, a special MRI of the lung has to be made in which the contrast is enhanced by helium.
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