What is magnitno - a resonant tomography?
are virtual to cut the person across and to look that it there inside, always was dream of the doctor - the diagnostician. Now it can be made by means of x-ray computer tomographs.
But is also other way: it is possible to execute a tomography with use of effect of a nuclear magnetic resonance (MR - a tomography). Such researches are widely applied around the world, and clinical experience testifies to high resolution and contrast of the received layer-by-layer images of bodies and fabrics. Actually photos of anatomic cuts manage to form the images equal on quality.
Besides in computer tomographs on the basis of effect of the nuclear magnetic resonance (NMR) there are no sources of ionizing radiation and therefore diagnostic testings on MR - tomographs are almost completely safe for patients.
The effect of a nuclear magnetic resonance was opened in 1946 by scientific groups at Stendfordsky and Harvard universities. His pioneers - F. Bloch (F. Bloch) and E. M. Pascrell (E. M. Purcell) - got the Nobel Prize on physics for 1952. They established that kernels of some atoms when placing them in a magnetic field absorb energy of an electromagnetic impulse, and upon termination of an impulse radiate it in the form of a radio signal. For emergence of such nuclear resonance the induction of a magnetic field and frequency of an electromagnetic impulse have to correspond definitely each other.
For the medical purposes the effect of a nuclear magnetic resonance is used since the beginning 80 - x years of the last century. The first MR - tomographs were shown on the congress of radiologists in Paris in 1982.
At the heart of MR - a tomography the principle of a magnetic resonance of kernels of hydrogen lies. As water contains in bodies and tissues of the person in a significant amount, respectively, hydrogen - the most widespread element in a human body.
The diagnostic testing occurs as follows. The patient is placed in a strong static magnetic field of MR - the tomograph then hydrogen atomic nuclei in a body of the person (which represent small magnetics) are guided in the direction of the field. The studied area is chosen, adding a weak variation magnetic field by means of so-called gradient coils. Then the tomograph sends an electromagnetic signal (radio wave); it becomes by means of a radiator of radio-frequency impulses. Atoms of hydrogen are excited and generate a reciprocal signal which is caught by reception radio-frequency coils - tomograph detectors. Different types of fabrics (bone, muscle, etc.) contain different amount of atoms of hydrogen therefore they generate signals with various characteristics. After decoding of signals the image of the corresponding layer is built (by a certain technique).
MR - the tomography began as the method giving the image of thin cross cuts of a body of the person. With development of the software from layer-by-layer images passed (also as well as in a x-ray computer tomography) to volume. Now this method is especially effective at research of dynamic processes (for example, conditions of a blood-groove) in bodies and fabrics.
In conclusion I will tell that MR - the tomograph on the appearance is similar to the x-ray computer tomograph; not the expert will hardly distinguish them.
in the course of research a table with the patient gradually moves ahead in the scanner executed in the form of a ring (gentra). When scanning the patient is in the tomograph tunnel where light-is enough and there is a fan providing inflow of fresh air. It is necessary that the patient did not move as even small shifts can significantly reduce quality of the received images. Duration of a diagnostic testing - of 30 minutes till one o`clock.]