[A method of electric simulation of the radionuclide dilution curve]. / Metod élektricheskogo modelirovaniia krivoi razvedeniia radionuklida.

The authors demonstrate a possibility of electric simulation of the radionuclide dilution curve for the laminar blood flow. The time required for the indicator mixing, the mean time of blood circulation, and transmission function of circulation in an organ can be derived as a result of such simulation.

[Automated evaluation of the central hemodynamic status using the RKA 3-01 Radiocardioanalyzer]. / Avtomatizirovannaia otsenka sostoianiia tsentral'noi gemodinamiki s pomoshch'iu radiokardioanalizatora RKA 3-01.

The authors presented the results of a clinical use of a new radiocardioanalyzer RKA 3-01 (manufactured in the USSR) providing for automated measurements and computations of indices of the central hemodynamics during studies using a method of dilution of radioactive nuclides. The main technical potentialities of the device designed on the basis of microprocessor technology, were described. The authors also provided the results of automated computation of the circulating blood volume and the main hemodynamic indices in a group of patients. Values of the hemodynamic indices were shown to correspond to actual ones and comparable to control ones and clinical evidence. The comparison of automated processing with a manual method of calculation indicated a significant coincidence of index values. The clinical use of the radiocardioanalyzer RKA 3-01 for automated assessment of the indices of the cardiovascular system was shown to hold promise among various groups of patients.

[Evaluation of the errors in analog recording of radionuclide dilution and clearance curves]. / Otsenka pogreshnosti analogovoi registratsii krivykh razvedeniia i klirensa radionuklidov.

The mathematical expression for the function of changes in the output signal of the analog medium frequency pulse meter (MFPM), supplied on the input of the dilution curve (clearance) of a radioactive indicator, is obtained. The graphs illustrating the deformation of the initial curve at different MFPM time constants and different rates of the increase and decrease in the input signal, corresponding to the real conditions occurring in the study of the regional cerebral and muscular blood flow with the use of 133Xe clearance and the study of the blood flow volume through heart and large vessels with the use of RISA-131 dilution, are plotted. The errors introduced by the MFPM to the obtained data of the basic informative parameters--a period of half-dilution, the maximum value and the area under the curve are calculated. The graphs of the errors versus the MFPM time constants are normalized by the time units relative to the maximum of the corresponding initial curves thus enabling one to use the graphs as a versatile means in the course of assessment of the dilution and clearance curves' distortions introduced by the analogous MFPM. The analysis of the results obtained is presented.

[Circulating blood volume meter]. / Izmeritel' ob''ema tsirkuliruiushchei krovi.

The article describes the functional diagram, calibration principle and operation of a new instrument, ur1-7. This device measures the volume of blood circulating in the organism by the radioisotope dilution method. The measurement range is from 1 to 9.9 1, with error not exceeding +/- 5%.

[New method of stroke volume measurements by means of radioactive isotopes]. / Novyi metod izmereniia udarnogo ob'ema serdtsa s pomoshch'iu radioaktivnykh izotopov

A new radioactive method of measuring the stroke volume called "radiocardiometry" is described, and the results of a clinical trial of the method are presented. The results were compared with those obtained by means of radiocardiography that was conducted simultaneously with the stroke volume measurements performed according to the suggested method. The results coincided with an approximation of +/- 10% in all cases, with the exception of those with mitral insufficiency in which the results obtained by means of radiocardiometry were 12--31% higher than those calculated from radiocardiography. The circulating blood volume was measured by the administered activity and by the activity of the sample without any preparation of standard solutions. The error in the measurements of this parameter did not exceed +/-5%.