RESUMO
BACKGROUND: Estimation of the left ventricular ejection fraction (LVEF) using myocardial perfusion imaging is increasingly used in the evaluation of coronary artery disease. This study aims to compare the effect of (i) two commercially available software packages: quantitative gated single-photon emission computed tomography (SPECT) (QGS) and 4DM-SPECT, and (ii) prereconstruction filtering, on LVEF quantification. METHODS: Images from 101 patients were reconstructed using AutoCardiac and processed using QGS and 4DM-SPECT. Filtering was performed before reconstruction using Hermes FBP SPET on a group of 32 consecutive patients using Butterworth filters (orders 5 and 10; cut-off frequency 0.5-1.2 cycles/cm). RESULTS: Good correlation was observed between QGS and 4DM-SPECT (r=0.88), with an average difference of 2.1%. The difference in LVEF between the two packages ranged from 21 to -28%. The LVEF was overestimated at cut-off frequencies < or = 0.8 cycles/cm compared with higher cut-off frequencies in 26 of 30 (87%) patients. CONCLUSION: There was a clinically significant difference between the LVEF calculated by QGS and 4DM-SPECT and consequently the two packages should not be used interchangeably. The effect of cut-off frequency on LVEF estimation was found to be very patient specific. Changing the cut-off frequency by as little as 0.1 cycles/cm can cause clinically significant differences in LVEF estimation.
