STSINTIGRAFIYA

From Big Medical Encyclopedia

STSINTIGRAFIYA (Latin scintibla a spark + Greek grapho to write, represent) — the method of a radio isotope research of internals based on visualization by means of the scintillation gamma camera of distribution of the radio pharmaceutical drug administered in an organism.

At S. always use the radio-pharmaceuticals (RP), marked gamma the radiating radionuclides (cm. Radio pharmaceuticals ), therefore S. name also gamma stsintigra-fiyey. The gamma cameras used to S. are supplied with the detector (a scintillation crystal), photoelectronic multipliers (FEM) and replaceable lead collimators. The sizes of a crystal and the corresponding collimator define «the field of vision» of the gamma camera (see. Radio isotope diagnostic units , Collimation ). The gamma quanta arriving through openings in the collimator from RFP distributed in a body of the patient excite in a crystal of flash scintillation, to-rye are considered by FEM, and at means of the electronic block form in a position signal on an electron beam tube. The photographic or polarized cameras put to an electron-beam tube allow to receive the photo or polarized images called by stsintigramma. Pages make as in the special room on stationary gamma cameras, and in chambers by means of mobile gamma cameras. The last is especially important at diagnosis of a myocardial infarction and disturbances of cerebral circulation. Modern scintillation gamma cameras are completed with the specialized COMPUTER, in memory a cut images of distribution of RFP in the explored area are registered. Unlike scanning (see) at S. account of radiation is kept at the same time on all field that gives the chance at registration of separate shots with an interval to 0,1 sec. to define the nature of movement of RFP in the studied body. For studying of an anatomo-topographical condition of internals and detection of the centers in them patol. distributions of RFP are usually limited to performance of one stsintigramma (a static stsintigrafiya). Make a series for studying of functions of internals stsintigramm during a certain time term (a dynamic stsintigrafiya). However and static S. can also give important information on function of nek-ry internals. So, e.g., at S. of kidneys after introduction the patient of RFP can count by means of the COMPUTER fraction of RFP in each kidney and to determine quantity of the functioning parenchyma by this indicator. At a research with colloid solutions, to-rye are normal absorbed generally in a liver (apprx. 90%), the increased their accumulation in a spleen is a sign of cirrhotic process in a liver. For nek-ry internals rather organotropic RFP are not found yet and in such cases use a technique of a so-called binuklidny research. E.g., apply to visualization of a pancreas selenometionin, marked 75Se, to-ry collects both in a pancreas, and in a liver. At increase in a liver it is impossible to select on a stsintigramma the image actually of a pancreas therefore at a pankreatostsintigrafiya to the patient enter not only selenometionin, but also colloid solution, marked 99m Tc, to-ry collects only in a liver. Consistently receive a stsintigramma of a liver and a pancreas after introduction 75Se, then only a liver on entered 99m Tc and by means of the COMPUTER «subtract» the second image from the first image — on a stsintigramma there is only actually a pankreatostsintigramma (see. Pancreas ).

Nek-ry techniques of static S. are based on obtaining diagnostic information on the increased accumulation of RFP in patol. center. E.g., at metastatic damage of a skeleton of RFP, being distributed in a bone tissue, collects in places of metastasises in bigger quantity that is displayed on stsintigramma in the form of «the hot centers» (see tsvetn. the tab. to St. Bone , fig. 3). Stsintigrafiya with osteotropny RFP in many cases allows to reveal metastasises of a tumor in a bone in 4 — 6 months prior to emergence them rentgenol. signs. In tumors of a brain owing to disturbance in a zone of defeat of a blood-brain barrier often there is a delay of RFP. Accumulation of RFP is displayed on stsintigramma in the form of the «hot center» corresponding to tumoral education. At a stsintigrafiya of a thyroid gland with 131 I receive the clear image of all gland. However at toxic adenoma of RFP collects only in patol. the center, and normally functioning fabric of gland on stsintigramma does not come to light. Only after introduction the patient of thyritropic hormone of the hypophysis stimulating function of a thyroid gland can receive the image of its normally functioning fabric on stsintigramma.

For S. of lungs use marked macro - and microunits of albumine of blood serum of the person, to-rye are late in capillaries of lungs, causing their embolization. For elimination of imposing of images of one segments of lungs on other S. of lungs do in various projections (polyposition, multiprojective S.). At S. of kidneys polyposition S. gives the chance to find small tumors. In need of a current of one research make S. of two bodies. E.g., at oncological patients for the purpose of differential diagnosis of the reasons of pains in lumbar area it is possible to make at the same time a radio isotope research of a skeleton and S. of kidneys after introduction of the corresponding RFP and to receive images of a skeleton and kidneys on one stsintigramma.

Given to a dynamic angiokardiostsintigrafiya in the form of the separate stsintigraficheeky shots reflecting various phases of advance of radio pharmaceutical drug on departments of heart and the main vessels (norm): and — a phase of filling of the right departments; — a pulmonary phase; in — a phase of filling of the left departments; (1 — an upper vena cava; 2 — the right auricle; 3 — a right ventricle; 4 — a pulmonary trunk; 5 — lungs; 6 — left went rods; 7 — the ascending aorta; 8 — an aortic arch; 9 — the descending aorta).

For a research of cordial activity use dynamic S. (fig). Dynamic S. is applied also at a research of function of kidneys (see. Renografiya radio isotope ).

Stsintigramma of internals can be written down in memory of the completing COMPUTER for the purpose of after-treatment of information, to a cut subtraction of a background, subtraction of certain levels of intensity, creation of histograms on different sites of the image of body belong, to-rye reflect intensity of the registered radiation in each point in the area of a cut, etc. At dynamic S. in computer memory a large number of shots during a certain time term is registered. After the end of a research of the image look through for the purpose of assessment of features of an anatomo-topographical state and function of the studied body. According to special programs of software of the COMPUTER make calculation of number of the registered impulses in each zone of interest, in each shot, and the received indicator in the form of a point of the COMPUTER automatically postpones on graphics where point time of receiving a shot to ordinate axes, and for abscissa axes — number of the registered impulses. Within one minute of the COMPUTER makes calculation of indicators from four zones of interest and automatically builds the schedule on the screen of the display, to-ry it can be photographed. The received curves allow to determine, e.g., with a big accuracy a condition of function of the hepatocytes taking from RFP blood, the course of filling of a gall bladder and a condition of a sphincter of Oddi (by quantity of RFP removed with bile in intestines). In the same way investigate also function of kidneys. Diagnosis of functional disturbances of internals by dynamic S.'s method allows to estimate with a big accuracy development patol. process and efficiency of the carried-out treatment.

In all cases at S. it is necessary to follow strictly rules of work with radioactive drugs (see), to carefully carry out control radiometry (see), and if necessary deactivation of rooms and the equipment. The quantity of the entered RFP at S. is calculated depending on type of the gamma camera and weight of the patient. After S.'s performance patients are deleted to the isolated room since they are sources of radiation. An exposure dose of the patient during the use of modern marked 99m Tc RFP does not exceed 1/10 marginal doses, established by «Standards of radiation safety». Restrictions for S. the same, as for any other method of radio isotope diagnosis (see).

See also Radio isotope research .



Bibliography: Zubovsky G. A. Gamma stsintigrafiya, M., 1978; it; Radio-isotope diagnosis in pediatrics, JI., 1983; Baum S. and. lake of Atlas of nuclear medicine imaging, N. Y., 1981; M an i s e at M. Nuclear medicine, L. a. o., 1980.


G. A. Zubovsky.

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