Quantitative Radiocardiography

Abstract

The theoretical and technical limits within which the cardiac output can be measured from a curve recorded by a precordial counter after injection of a gamma-emitting tracer have been assessed. The geometric arrangements that best approach ideal conditions have been described. It has been shown that the physiologic significance of the value for output as measured from the radiocardiograms varies with the indicator-flow ratio in the two sides of the heart. The necessary conditions for measurement of right ventricular volumes from the radiocardiograms have been presented, and the theoretical limits of the technique are evaluated. The problem of the measurement of pulmonary blood volume from radio-iodinated serum albumin (RIHSA) radiocardiograms has been discussed. While it is not possible to make a direct measurement of mean pulmonary blood volume from RIHSA radiocardiograms, the limits within which this volume lies have been indicated.