[en] Full text: The quantitative gated SPET (QGS) algorithm is a commercially available software package which uses ⁹⁹Tc^m-Sestamibi (MIBI) SPET gated short-axis images to automatically derive endocardial surfaces and compute ejection fraction (EF). This project compares automatic QGS EF measurements with those from gated heart pool scanning (GHPS) for the same patients. In addition, EF measurements from QGS were compared with those from a first generation, manual edge definition gated SPET EF package (SPETEF (GE)). The automatic and semiautomatic QGS methods were compared for this group of patients. A GHPS was performed on 17 patients suspected of coronary artery disease within 4 days of their gated MIBI SPET myocardial perfusion study. All QGS and GHPS analyses were performed on a GE-Genie system. EF calculated using QGS showed a correlation of 0.82 with EF calculated from GHPS. A paired t-test showed no significant differences between the 2 groups. However, a Bland-Altman analysis of agreement showed a trend for QGS measurements to be slightly higher over the whole range of EFs encountered. Comparison of SPETEF and QGS measurements revealed a good correlation (0.91) and good agreement over the EF range. Despite a very high correlation (0.97), automatic QGS EFs were consistently higher than semi-automatic QGS measurements by an average of 3.5 percentage points. In conclusion, a relatively high correlation and agreement exist between QGS, GHPS and SPETEF measurements. A tendency for the automatic QGS method to produce slightly higher measurements than GHPS and the semi-automatic QGS method was detected