Magnetic-resonant tomography

Magnetic-resonant tomography (MRT) - tomography method of research of internal bodies of the person with use of the physical phenomenon of a nuclear-magnetic resonance - the method is based on measurement of the electro-magnetic response of atoms of hydrogen on excitation by certain combination of electro-magnetic waves in a constant magnetic field of a high tension. The method of a nuclear magnetic resonance (nuclear magnetic resonance) is based on interaction of an external magnetic field with the nucleus having the magnetic moment, for nucleus with nonzero spin, for example ¹Н, ¹³С, ¹⁵N, ³¹P. Spectroscopy of a nuclear magnetic resonance on nucleus ¹Н now is most developed and has received the name a proton magnetic resonance (PМR). The same nucleuses of atoms in various environments in a molecule show various signals of a nuclear magnetic resonance. Difference of such signal of a nuclear magnetic resonance from a signal of standard substance allows defining chemical shift which is caused by a chemical structure of studied substance. In techniques of a nuclear magnetic resonance there are many opportunities to define a chemical structure of substances, conformations of molecules, effects of mutual influence, intramolecular transformations.

The image of a brain of the person Tomography image of a head of the person on a medical tomograph

The principle of work of a magnetic-resonant tomograph is based on nuclear-magnetic a resonance of atoms of substance in a strong magnetic field. In comparison with x-ray methods, for example a computer tomography or the usual x-ray picture, the given method is not connected with getting radiations and consequently it is considered the most safe nonivasive method of research now. Physical principles of construction МR images allow receiving images not only a bone tissues, but also soft tissues of a joint, such as copulas, cartilages, hyaline layer and muscular tissues.

This method allows receiving level-by-level images of an investigated part of a body with any spatial arrangement of layers. The patient is located in a strong magnetic field; it leads to that all atoms of hydrogen in a body of the patient are built in parallel a direction of a magnetic field. The device sends an electromagnetic signal to this moment, is perpendicular to the basic magnetic field. The atoms of hydrogen having identical frequency with a signal, "are raised" and generate the signal which is caught by the device. Different kinds of tissues (a bone, a muscle, and vessels) have various quantity of atoms of hydrogen and consequently they generate a signal with various characteristics. The tomograph distinguishes these signals, will decode them and builds the image. Magnetic-resonant tomography - the most valuable method of research of a bone brain as has opened ways of detection of a hypostasis, necrosis and a heart attack of a bone brain and initial displays of pathological processes in a skeleton. The magnetic-resonant tomography gives opportunity to the doctor to study morphology and biochemistry of cartilages and soft tissues of musculoskeletal system. МRТ, for example, it is shown at suspicion on break of copulas and for exception of a herniation of intervertebral disk. Very widely МRТ use in neurosurgery and neurology (old traumas of a brain, insults in late (!) stages, suspicions on a tumour of spinal cord and a brain). During carrying out of scanning the patient is in the tunnel of the device. In the tunnel of the scanner good illumination, also is the fan which blows in the patient and provides inflow of fresh air. Research passes from 30 up to 60 minutes. In a room where the scanner is located, it is impossible to bring metal subjects (hours, coins, credit cards, phones) - the strong magnet of the scanner can damage them, and received images will be poor quality because of distortion of a magnetic field.

МRТ has counter-indicative for the patients, suffering by claustrophobia and having alien metal inclusions (artificial metal joints, bullet splinters).

Comparison of a x-ray picture and МР tomograms of a knee-joint.

X-ray picture The tomogram

Examples of tomograms

Ultrasonic (Ultrasonic diagnostics, echography).

Ultrasound is the most modern, and also one of the most informative methods of diagnostics of the majority of diseases, including gynecology. In what advantage of ultrasonic before other, not less modern methods of diagnostics? Absolute harmlessness for the patient is basic advantage of ultrasonic. It does not render any harmful influences on an organism, there is no beam loading. Therefore, if the doctor or the patient requires specification of the put diagnosis, procedure of ultrasonic always can be repeated without superfluous fears. In this connection it is necessary to mention uniqueness of the given method when within the limits of one reference to the doctor it is possible to carry out ultrasonic research of many bodies and systems of an organism.

The method of ultrasonic - diagnostics takes leading positions in diagnostics of the majority of diseases of bodies of a belly cavity, urination systems, a thyroid gland, salivary and mammary glands, heart. Probably, it is easier to tell, where use of ultrasonic is impossible or is limited. It are diseases of bone system, lungs, a gastroenteric path, a brain. But even in the given areas every year even more often address to a ultrasonic method of diagnostics.

Ultrasonic is widely applied in gynecology. Diagnostics of diseases of bodies of female sexual sphere is spent by means of ultrasonic. In obstetrical practice ultrasonic have a big meaning at an estimation of processes of pre-natal development of a foetus. The obstetrician-gynecologist has an opportunity to investigate all bodies of a foetus with the purpose of revealing of defects, and also to supervise stages of normal development of pregnancy. The conclusion received by results of similar ultrasonic research, will help various doctors-experts to estimate most objectively a degree of pathology and to relieve the patient of vain anxiety.

Ultrasonic research is a research of a condition of bodies and tissues by means of ultrasonic waves. In a homogeneous environment ultrasonic waves extend rectilinearly and with constant speed. With unequal acoustic density the part of rays is reflected in border of environments, and the part refracts, continuing rectilinear distribution. The above the gradient of difference of acoustic density of boundary environments, the most part of ultrasonic fluctuations is reflected. At reflection from moving object (for example a blood-groove in vessels) frequency of the reflected signal changes (Doppler's effect), that allows to calculate relative speed (on shift of frequency). The special sensor (as a rule, is both the receiver, and the transmitter) fixes the reflected signal - these data and are a basis for reception of the ultrasonic image.

Intensive development and perfection of medical ultrasonic engineering is based on use of scientific bases radio-location and hydro-locations, digital electronics, semi-conductor engineering. Modern medical ultrasonic scanners allow to receive three-dimensional images of objects with resolution up to 0,1 mm, Doppler’s principles allow to estimate a blood-groove in vessels, movement of walls of hearts and other tissues of a body of the person with speeds less than 1 cm/sec.

Color Doppler allows making allocation on echogram (color mapping) character of a blood-groove in the field of interest by color. It is accepted to map a blood-groove to the sensor by red color, from the sensor - dark blue color. A turbulent blood-groove is mapped by cyan-yellow color.

Color Doppler is applied to research of a blood-groove in vessels, in an echocardiography. Other names of technology - color Doppler’s mapping (CDM), color flow mapping (CFM) and color flow angiography (CFA).

Usually by means of color Doppler, changing position of the sensor, it is possible to find area of interest (vessel), then for a quantitative estimation pulse Doppler is used.

Color and power Doppler help with differentiation of cysts and tumors as internal contents of cyst are deprived vessels.

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