Reproducibility of ejection fraction measurements by gated equilibrium blood pool scintigraphy

The reproducibility of ejection fraction measurements has been studied using gated equilibrium blood pool scintigraphy. The use of appropriate statistical tests is proposed and commented upon. The intra-observer variability for our group of patients has a standard deviation of 6.4%, the interobserver variability of 3.2% and sequential studies done on the same and different days give standard deviations (due to "time" alone) of 1.0% and 1.9%, respectively. Different factors and sources involved in variability are mentioned. Variability values reported in the literature are discussed.