A comparison of 8 and 16 frames gated SPECT imaging for determination of left ventricular volumes and ejection fraction: effects of gender and myocardial counts.

In myocardial gated SPECT imaging each cardiac cycle is divided into 8 or 16 temporal frames and the cause of the difference between 8 and 16 frames is not specified exactly. The aim of this study was to investigate the effect of myocardial detector counts and gender on the difference between 8 and 16 frames and also to compare the LVEF obtained by 8 and 16 frames with echocardiography. The study population included 84 patients who underwent gated SPECT imaging. Left ventricular parameters were assessed on 8 and 16 frames gated SPECT. LVEF was also measured with two-dimensional echocardiography within 5-10 days after gated SPECT imaging. There was a good correlation between 8 and 16 frames for calculation of LVEF (p = 0.00, r = 0.860), EDV (p = 0.00, r = 0.965) and ESV (p = 0.00, r = 0.956) in all patients. But the difference between 8 and 16 frames for calculation of LVEF (p = 0.00), EDV (p = 0.014) and ESV (p = 0.00) was statistically significant. This difference was assessed separately in females, males, patients with high photon counts and patients with low photon counts and in all subgroups was statistically significant difference in the estimation of LVEF and ESV (p < 0.05) but no significant difference in the estimation of EDV (p > 0.05). Echocardiography resulted in smaller LVEF as compared to 8 and 16 frames gated SPECT studies and there was a significant difference between the two methods (p = 0.00). The myocardial detector counts and gender have no effect on the difference between 8 and 16 frames methods and the LVEF on echocardiography is smaller than the gated SPECT, but the 8-frame is closer to echocardiography.