Evaluation of the Left Ventricular Ejection Fraction with Gated IQ-SPECT Myocardial Perfusion Imaging

The aim of this study was to evaluate the assessment of the left ventricular ejection fraction (LVEF) in patients by gated IQ-SPECT.

Twenty-eight patients were examined using gated (99m)Tc-sestamibi IQ-SPECT. Two different reconstruction datasets were created using the same projection data. The number of iterations, subsets, and gaussian filtering were based on 2 different recommendations from the manufacturer. For each dataset, end diastolic volume, end systolic volume, and LVEF were calculated using 4DMSPECT. A multigated planar equilibrium radionuclide ventriculography (MUGA) study with (99m)Tc-labeled red blood cells was used as a reference for the LVEF.

The values of the different datasets were tested using the Bland-Altman analysis method. The calculated mean and 95% limits of agreement for the LVEF when dataset 1 and 2 were compared were -1.1% and ±15% points; when dataset 1 was compared with MUGA, the mean was calculated to -3.1% points and ±17% points for the 95% limits of agreement. When dataset 2 and MUGA were compared, the mean was -4.2% and 95% limits of agreement of ±18% points.

Neither of the gated reconstructed datasets analyzed with 4DMSPECT was comparable to LVEF estimated by MUGA, with a tendency to overestimate LVEF. However, large random variations of the end diastolic volume, end systolic volume, and LVEF between the 2 gated reconstructed datasets were found. The reconstructed datasets were not interchangeable. Thus, these values should only be used with great caution when evaluating the functional state of the heart.