Right ventricular ejection fraction: comparison of technetium-99m first pass technique and ECG-gated steady state krypton-81m angiocardiography.

Right ventricular ejection fraction (RVEF) calculated from ECG-gated steady-state 81mKr angiocardiography and from 99mTc first-pass studies were compared in 30 patients using a digital, single crystal, gamma-camera. Despite the two entirely different approaches RVEF values obtained by the two methods were comparable (r = 0.97): the mean absolute difference between the two techniques was 2.5% +/- 1.5% and the largest observed absolute difference was 5%. In the absence of an accepted reference method for measuring RVEF, this close correlation provides indirect validation of both techniques. The choice of method will therefore depend on several factors, including radiotracer availability, the characteristics of the gamma-camera and the protocol of clinical investigation.