Estimation of left ventricular ejection fraction (EF) by videodensitometry

Digital subtraction left ventriculograms were obtained in 17 patients.The ventriculograms were analyzed by videodensitometry（VIDEO）,and density-time curves were constructed.EF was obtained by subtracting the density values of end-systole from that of end-diastole,and dividing the difference by the latter density value.Correlation was made between EFs by VIDEO and arealength methods.The correlation coefficient was 0.93,P＜0.001.The serial EFs by these two methods were plotted as the function of systolic interval.The results showed that the serial EFs by the area-length method rose ealier and faster than the serial EFs by VIDEO.It is concluded that EF can be accurately measured by VIDEO.However,several physical factors may prevent X-ray attenuation from being linearly proportional to the depth of iodine contrast.