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Biomedical subjects

I N Gel'fand

Publications and source records attributed to I N Gel'fand.

17 recordsLinked to original sources
PubMed1987

[Method of determining separate kidney clearance].

The task was to develop a simple and effective method of radionuclide determination of separate clearance of the kidneys (SCK), i.e. separate assessment of secretory-excretory function of each kidney. The other earlier known methods of SCK determination were either methodologically incorrect or very difficult. A method of SCK determination intended both for gamma-chambers and standard radiographic units based on common renographic methods, was proposed. An algorithm for processing of measurement results was based on the generalization of the mathematical apparatus of circulation models usually employed for a study of the central and organ hemodynamics, and on its development for transitory nephrotropic radiopharmaceuticals (RP). An investigation of 21 healthy persons and 51 patients with renal tumors using 131I-hippuran showed that the proposed method possessed sufficient sensitivity for its clinical use. Advantages and shortcomings of the method were analysed. All the allowances were justifiable.

Humans↗
PubMed1985

[Radionuclide study of liver hemodynamics].

A new method for processing the results of radionuclide studies on the liver blood circulation was proposed. It permitted assessing the state of the liver vascular network by a system of indicators having a specific physiological meaning: the ratio of functioning volumes of the vascular bed of the arterial and portal systems, the general, arterial and portal liver blood circulation in cardiac output fractions. The application of the method to radionuclide studies on the liver blood circulation in 5 healthy persons and 15 patients with metastatic liver lesions showed its efficacy and clinicodiagnostic significance.

Hemodynamics↗
PubMed1984

[Clinical significance of the size of the necrotic area and the rate of its formation in the acute period of myocardial infarct].

The authors suggest a new method of interpreting the kinetics of the isoenzyme MB CPK in the body based on mathematical modelling. This method have made it possible to increase the accuracy of determining the necrotic size and to calculate the temporal parameters (rate and acceleration) of the formation of the necrotic focus. The studies have shown that these temporal parameters allow the timely (within the first 10-12 h of the disease) objective and quantitative assessment of the disease severity. The proposed method of interpretation was used in the biochemical examinations of 128 patients with acute myocardial infarction and the results obtained indicate its clinical-diagnostic and prognostic value.

Adult↗
PubMed1984

[Radionuclide study of reticuloendothelial system function].

The authors propose a new method for the interpretation of the measurement data obtained during radionuclide investigations of the function of the reticuloendothelial system (RES). This method is upon the concept of a considerable effect of the blood opsonizing factor on the transport of i.v. injected radioactive colloid in the body. A non-linear compartmental model was developed that describes the binding of colloid particles with opsonins in the vascular bed followed by absorption of the particles of the colloid-opsonin complex by RES cells. The identification of the parameters of the non-linear model by the results of dynamic scintigraphy of the heart and liver makes it possible to explain some phenomena in the measurement data and to assess the relative amount of opsonins in the blood and RES phagocytic activity as a whole and its constituents. It was shown in particular in the studies on patients with hepatocirrhosis that the amount of opsonins in the blood remains almost the same as compared to the normal one whereas the phagocytic activity of RES on the whole, hepatic stellate cells and RES extrahepatic cells decreases significantly.

Colloids↗
PubMed1983

[Radiocardiogram interpretation by estimating the average transit time of a tracer].

A new method for the interpretation of the radiocardiographic (RCG) data is proposed. As distinct from the widely used method developed by Donato et al. based on the exponential extrapolation of the terminal zones of the RCG peaks and the calculation of the mean time of the indicator general circulation in the body, this one is based on the approximation of both RCG peaks by gamma-image function, measurement of the indicator maximum level in the field of interest of the vena cava superior and calculation of the time indices that characterize the mean-transit time of radioactivity through the right cardiac regions and through the heart and lungs in general. On examination of practically healthy persons and 62 patients with ischemic heart disease 10 different RCG time indices were identified. The correlation matrix of the interrelationships of these indices and the matrix of the coefficients of respective regression equations were calculated. It has been established that the mean time of general circulation results in the distorted evaluation of myocardial pump function whereas time indices determined by the above method give a more adequate evaluation of the central hemodynamics.

Coronary Disease↗
PubMed1983

[Determination of the temporal characteristics of tracer transport in hemodynamics studies].

A novel method designed for processing the findings obtained from radionuclide studies of hemodynamics is proposed. This technique is based on the establishment of the mean time needed for the transit of the indicator through the studied physiological structure which is done by determining its transport function. Temporal division of information concerning the right and left departments of the heart suggested by the authors for the preliminary processing of radiocardiographic data has a number of advantages over the current techniques. The application of the proposed method for interpreting radiocardiograms in 74 patients with compromised circulation showed that the determination of the mean time of the indicator transit whose magnitude alters significantly depending on the severity of the disease enables the objective evaluation of the state of the physiological system studied.

Adult↗
PubMed1983

[Comparative evaluation of the changes in MB CPK activity and indices of precordial mapping].

Twenty patients with acute myocardial infarction were investigated, with simultaneous peripheral blood MV CPK activity measurement and precordial charting. Extreme values of precordial charting compared to those of MV CPK activity peaks as well as the duration of increased MV CPK activity showed that extreme precordial charting values can be detected 6-9 hours later than peaks of MV CPK activity. Necrosis weights estimated on the basis of MV CPK activity and precordial charting parameters showed close correlation. The results obtained suggest that MV CPK activity measurement is a more accurate method of assessing the spread of necrotic zone, whereas precordial charting provides a more accurate estimation of necrosis weight.

Creatine Kinase↗
PubMed1982

[99mTc-pyrophosphate scintigraphic indices during the bicycle ergometry test in myocardial infarct in the early phase of healing].

Scintigraphy with 99mTc-pyrophosphate during bicycle ergometry has been undertaken in 32 patients with myocardial infarction in the early phase of its healing. There were 3 scintigraphic investigations: one during bicycle ergometry and two control ones - before and the day after the test. The determination of changes in the degree of 99mTc-pyrophosphate accumulation under the influence of the exercise in patients with myocardial infarction in the early phase of its healing permitted the authors to detect several variants in the time course of scintigraphic values. Drop or rise of concentration of the labelled pyrophosphate at the height of the bicycle ergometry test compared to the data obtained prior to it are apparently due to changed bloodflow in the focus of lesion during exercise. Changes in the character and intensity of accumulation of the radiodrug after bicycle ergometry can be explained in the majority of cases by increase of metabolic disorders in the myocardium, supervening during the exercise, and in some patients, possibly, to sustained decrease of bloodflow in the affected area of the cardiac muscle.

Adult↗
PubMed1981

[99mTc-pyrophosphate scintigraphic indices at different times in acute myocardial infarct].

The incorporation rate of 99mTc-pyrophosphate into the myocardium was studied in 123 patients with acute myocardial infarction at different stages of the disease. The capacity of the damaged myocardium to accumulate the labelled pyrophosphate decreased with its healing. The accumulation character of the radiopharmacologic preparation also changed. The revealed phenomena are explained by the features of the 99mTc-pyrophosphate concentration mechanisms of the damaged areas of the myocardium. during the necrosis phase pyrophosphate is accumulated in the irreversibly damaged myocardial cells. The incorporation of 99mTc-pyrophosphate into the myocardium at the late stages of the disease are explained by both the presence of the necrotized cells in the myocardium and possible binding of the radiopharmacologic preparation to collagen.

Diphosphates↗
PubMed1981

[Anatomical and biochemical methods of determining the extent of myocardial infarct].

Twenty patients who died in the acute (necrotic) period of myocardial infarction were examined. The activity of MB creatinephosphate kinase was tested in all of them every 4 hours till the activity of the enzyme was normal. The boundaries of the lesion were determined. The boundaries of the lesion were determined during post-mortem examination by the method of nitroblue tetrazole stain, and the mass of the lesion was measured after excision of the necrotic myocardium. A high degree of correlation between the true mass of necrotized myocardium and the biochemical measure of necrosis was found (r = 0.698), which enabled the authors to derive a regression equation for determining the true mass of the affected myocardium (in g) in the live patient.

Adult↗
PubMed1980

[Pyrophosphate-99mTc scintigraphy in stenocardia patients].

The authors examined 166 patients with ischemic heart disease and attacks of angina pectoris and 21 healthy individuals. Scintigraphy, electrocardiography and tests for the activity of creatine phosphokinase and its MB fraction were carried out at rest, during physical exercise and 1--3 days after it. It was found that pyrophosphate-99mTc may accumulate in the myocardium both during the attack of angina pectoris and after its cessation. Angina pectoris may occur both with diffuse and with focal pyrophosphate-99mTc accumulation in the myocardium. Positive results of scintigraphy were encountered considerably more often in patients examined during physical exercise than in those examined at rest. Scintigraphic signs of angina pectoris which occurs under the effect of physical exertion develop less frequently, but persisted for a longer time than its electrocardiographic signs.

Adult↗
PubMed1979

[Importance of pyrophosphate-99mTc scintigraphy in the diagnosis of acute myocardial infarct].

Scintigraphy with pyrophosphate 99mTc was performed in 230 patients with various forms of ischemic heart disease and in 15 persons with pain in the region of the heart caused by osteochondrosis of the cervical and thoracic spinal segments or vegetovascular dystonia (control group). It was found that labelled purophosphate accumulated in the myocardium in necrosis of the heart muscle or when coronary insufficiency takes a course in which necrosis of the myocardial cells is quite possible. Positive results of scintigraphy with pyrophosphate 99mTc are not a strict criterion of acute myocardial infarction because they are also encountered in a chronic course of ischemic heart disease and are evidence in this case that "a state of risk" has occurred during the disease.

Acute Disease↗
PubMedDate not supplied

[Effect of detector sensitivity on the accuracy of results of radionuclide kidney studies].

In the course of both kidney gammachronography with an isolated detector and kidney scintigraphy with a gamma camera the detector volume sensitivity is calculated. Mathematical model of the kidney is described as a set of superimposed linear-circular cylinders. Based on the CT examinations a cylinder radius and a thickness of soft tissues attenuating gamma radiation are derived. The detector volume sensitivity is found to change up to 34% in kidney gammachronography and up to 22% in kidney scintigraphy when using low power radionuclides.

Humans↗