Estimation of left ventricular ejection fraction by DSA videodensitometry

To estimate the effects of beam hardening, x-ray scatter and veiling glare on measurement of left ventricular ejection fraction (LVEF), relative volumes of a balloon phantom were measured using videodensitometry. The ejection fractions were measured by videodensitometry and geometrical method (area-length and Simpson's method) using an irregularly shaped balloon phantom which was modeled on a deformed left ventricular cavity. Calculations and phantom experiments suggest that the effects of x-ray scatter and beam hardening are negligible by using 12:l grids and iodine contrast media with low concentration (less than 10%). Moreover, the time density curves of contrast media for the heart in 8 patients revealed that the concentration less than 10% would be obtained in the left ventricle after peripheral intravenous administration of 30 ml with 76% urografin. The ejection fractions of deformed balloon phantom obtained by videodensitometry were compared with those by geometrical methods. The results indicate that videodensitometry provides more accurate estimations of the ejection fraction than the other two methods. Therefore, I believe that videodensitometry of DSA is a very useful method to estimate LVEF. (J.P.N.)