Evaluation of left ventricular ejection fraction by multi-gated radionuclide cardioangiography

A noninvasive, radionuclide, blood-pool imaging technique (multi-gated method) has been developed using a scintillation camera and on-line mini-computer system. In this study, the accuracy and validity of this MUGA method were examined in the fifty patients with cardiac catheterization. After sup(99m)Tc-HSA was injected intravenously, at the equilibrium stage, the scintillation data were stored in frame modes, in computer core memory using R-wave synchronizing phase, such that each of sequential image represented R-R/20 sec segments of the cardiac cycles summed over several hundred cycles. The ejection fraction was calculated by the formula; (EDV-ESV)/EDV counts from the left ventricular curve. The results correlated well with those obtained by biplane cineangiography in various cardiovascular diseases (r = 0.902) and moreover, between the same patients with MUGA method and first pass method good correlation of the ejection fraction (r = 0.82) was obtained. The findings, however, demonstrated that the region of left ventricle must be determined precisely and must be excluded the aortic valvular areas as background in order to accurate calculation of the ejection fraction. For the data collection, matrix size, number of frames, gate tolerance must be determined precisely to obtain high resolution gated scintigraphy as MUGA method. In conclusion, these findings demonstrate the validity of this technique in the atraumatic qualification of ventricular functions and suggest its usefulness in a variety of clinical conditions. (author)