Impact of Valve Plane Alignment on the Repeatability of Left Ventricular Ejection Fraction in ECG-gatedMyocard ial SPECT Using Corridor 4DM.

Background: In myocardial gated single-photon emission computed tomography (GSPECT), to differentiate true changes of left ventricular ejection fraction (LVEF) from inherent methodical variability is clinically relevant; however, data about repeatability of GSPECT LVEF in the same patients are rather inconsistent in literature. The aim of this study was therefore to determine repeatability coefficient (RC) of GSPECT LVEF at rest and to investigate the effect of the introduction of processing constraints in left ventricular edge detection. Methods: Thirty-five patients referred for one-day myocardial GSPECT stress-rest scan were included. After the routine stress-rest study, patients were completely repositioned on the imaging table for a second rest acquisition using the same acquisition parameters. LVEF was computed using Corridor 4DM software without and with manual alignment of valve plane. Repeatability was assessed using the Bland-Altman method. Results: RC of LVEF from unaligned datasets was 7.6% with upper and lower limits of agreement of 7.4% to -7.8%. After valve plane and ventricular long-axis length alignment, RC improved to 3.6% with upper and lower limits of agreement of 3.4% to -3.8%. Conclusions: RC using unaligned determination of GSPECT LVEF was comparable to that from previous publications. However, RC using valve plane alignment could be improved to below 4% on 95% confidence level.