Reliability of data obtained by radionuclide angiocardiography in follow-up studies with special reference to intra- and interobserver variations

The reproducibility of the data obtained by radionuclide angiocardiography was studied in terms of the intra- and intervariations of three technicians. Three parameters were chosen: The left ventricular ejection fraction (LVEF), the 1/3 filling fraction (1/3FF), and the ratio of the time from end systole to the point of peak filling rate against the entire diastolic period (TRPFR). First, each technician studied an independent consecutive series of 40 patients for the initial analysis. The original data of each patient, composed of 26 frames for one beat, were stored on an optical disc for the intra- and intervariation studies. In this study, analysis of the volume curve was performed by using both 3rd order and 4th order Fourier series. The region of interest (ROI) for the left ventricle, which was set for the initial analysis, was recorded by Polaroid photography to be used as a reference for the later analyses for the variation studies. The least variation was noted in the LVEF not only for the intravariation study but also for the intervariation study, no matter which order of the Fourier series was used. However, the 3rd order Fourier series seemed to give better curve fitting to avoid fluctuation of the diastolic parameters. The results indicate that we can expect more steady and reliable information from LVEF than from the diastolic parameters, even when various technicians perform the follow-up study of a particular patient.