RESUMEN
OBJECTIVE: The association between left ventricular (LV) dyssynchrony parameters, given by phase analysis of gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), and acquisition orbits is unclear. The aim of this study was to assess the dependence of LV dyssynchrony parameters on acquisition orbits. METHODS: Ninety-nine patients who underwent 201Tl-gated SPECT MPI were categorized into minor hypoperfusion or major hypoperfusion groups. Forty-four patients who underwent 99mTc-tetrofosmin-gated SPECT MPI were categorized into minor hypoperfusion or major hypoperfusion groups. The major hypoperfusion group with 201Tl was divided into inferior or non-inferior wall hypoperfusion subgroups, and anteroseptal or non-anteroseptal wall hypoperfusion subgroups. Gated SPECT MPI data over a 360° acquisition orbit (360° images) and a 180° acquisition orbit (180° images) were reconstructed, and histogram bandwidth (HBW) and phase standard deviation (PSD) were compared. RESULTS: Between 360° and 180° images with 201Tl, there were significant differences in HBW and PSD both globally (HBW 34.8 ± 16.6 vs. 29.1 ± 10.2; PSD 8.8 ± 4.9 vs. 7.0 ± 2.3, p < 0.05 for both) and in the inferior wall (HBW 29.5 ± 15.5 vs. 23.3 ± 9.0; PSD 7.6 ± 4.6 vs. 5.6 ± 2.4, p < 0.001 for both) in the major hypoperfusion group, and also in the inferior wall in all subgroups of the major hypoperfusion group. In contrast, no segment had any significant differences in HBW or PSD between 360° and 180° images with 99mTc. CONCLUSION: Differences in acquisition orbit had a significant influence on HBW and PSD with 201Tl-gated SPECT MPI in the inferior wall in patients with major hypoperfusion myocardium.