[Determination of ventricular volumes by a non-geometric method using gamma-cineangiography]

The authors suggest a new way of determining ventricular volume by a non-geometric method using gamma-cineangiography. The results obtained by this method were compared with those obtained by a geometric methods and contrast ventriculography in 94 patients. The new non-geometric method supposes that the radioactive tracer is evenly distributed in the cardiovascular system so that blood radioactivity levels can be measured. The ventricular volume is then equal to the ratio of radioactivity in the LV zone to that of 1 ml of blood. Comparison of the radionuclide and angiographic data in the first 60 patients showed systematic values--despite a satisfactory statistical correlation (r = 0.87, y = 0.30 X + 6.3). This underestimation is due to the phenomenon of attenuation related to the depth of the heart in the thoracic cage and to autoabsorption at source, the degree of which depends on the ventricular volume. An empirical method of calculation allows correction for these factors by taking into account absorption in the tissues by relating to body surface area and autoabsorption at source by correcting for the surface of isotopic ventricular projection expressed in pixels. Using the data of this empirical method, the correction formula for radionuclide ventricular volume is obtained by a multiple linear regression: corrected radionuclide volume = K X measured radionuclide volume (Formula: see text). This formula was applied in the following 34 patients. The correlation between the uncorrected and corrected radionuclide volumes and the angiographic volumes was improved (r = 0.65 vs r = 0.94) and the values were more accurate (y = 0.18 X + 26 vs y = 0.96 X + 1.5).(ABSTRACT TRUNCATED AT 250 WORDS)