Assessment of left ventricular volume and ejection fraction: comparison of QGS and MBGS analyses of ECG-gated myocardial perfusion SPECT imaging.

Objectives: The purpose of this study was to compare quantitative ECG-gated single-photon emission computed tomography (SPECT) (QGS) and model-based ECG-gated single-photon emission computed tomography (MBGS) for determination of end-diastolic cardiac volume (EDV), end-systolic cardiac volume (ESV), and left ventricular ejection fraction (LVEF). The accuracy of both methods was evaluated by measurements obtained from contrast left ventriculography (LVG).

Methods: Forty-five patients (40 male, age: 55+/-11 years) with coronary artery disease were studied by angiography and ECG-gated SPECT using technetium-99m-sestamibi for the evaluation of myocardial perfusion and LVEF. Short axis SPECT images were analyzed by QGS and MBGS to estimate endocardial and epicardial surfaces and to derive EDV, ESV, and LVEF.

Results: EDV by gated SPECT (QGS: 187+/-71 ml; MBGS: 191+/-76 ml) were lower than corresponding values by LVG (203+/-59 ml), whereas ESV by gated SPECT (QGS: 121+/-62 ml; MBGS: 108+/-54 ml) were higher than by LVG (105+/-49 ml). Thus, LVEFs by gated SPECT (QGS: 39+/-12%; MBGS: 45+/-9%) were significantly lower than by LVG (50+/-15%). LVEF by MBGS was significantly higher than by QGS (P<0.05). A significant correlation was observed among QGS, MBGS, and LVG for the calculation of EDV, ESV, and LVEF.

Conclusion: Measurements of LV volumes and LVEF by QGS and MBGS showed close agreement with each other and with results from LVG. However, both methods measure lower values for EDV and higher values for ESV and thus underestimate LVEF compared with LVG.