Performance of 8-vs 16 ECG-gated reconstructions in assessing myocardial function using Rubidium-82 myocardial perfusion imaging: Findings in a young, healthy population

BackgroundCurrent imaging guidelines recommend using at least 16 ECG gates when performing MUGA and cardiac SPECT to assess left ventricular ejection fraction (LVEF). However, for Rubidium-82 (Rb-82) PET, 8 ECG-gated reconstructions have been a mainstay. This study investigated the implications of quantitative assessments when employing 16 gate, instead of 8 gate, reconstructions for Rb-82 myocardial perfusion imaging (MPI).MethodsThe study comprised 25 healthy volunteers (median age 23 years) who underwent repeat MPI sessions employing Rb-82 PET/CT. We report LVEF, its reserve (stress LVEF - rest LVEF), and their repeatability measures (RMS method) obtained for 8- and 16 ECG-gated reconstructions.ResultsSimilar LVEF and LVEF reserve estimates were found for the 8- and 16-gated reconstructions ([%] LVEF (8/16 gates): rest = 61 +/- 6/64 +/- 6, stress = 68 +/- 7/71 +/- 6, LVEF reserve (8/16 gates): 8 +/- 3/6 +/- 4, and all P >= 0.13). Similar test-retest repeatability measures were observed for rest and stress LVEF and their reserves [LVEF (8/16 gates); Rest = 4.5/4.6 (P = 0.81), Stress = 3.5/3.2 (P = 0.33), LVEF reserve = 46.7/49.3 (P = 0.13)].ConclusionIn healthy subjects, 8 and 16 ECG gates can be used interchangeably if only volumetric assessments are desired. However, if filling and emptying rates are of interest, a minimum of 16 ECG gates should be employed.