Abstract 5819: Gated Myocardial Perfusion SPECT Underestimates Left Ventricular Volumes and Shows High Variability Compared to Cardiac MRI - A Comparison of Four Different Commercial Programs
INTRODUCTION: ECG-gated myocardial perfusion SPECT (MPS) can evaluate myocardial function by quantifying left ventricular volumes and ejection fraction. The accuracy and precision for these measures assessed by different commercially available programs, compared to each other and to the reference standard MRI, are largely unknown.
AIMS: To compare quantification of left ventricular volumes and ejection fraction by different MPS programs with each other and to MRI.
METHODS: N= 100 patients with known or suspected coronary artery disease were examined at rest with 99m-Tc-tetrofosmin gated MPS with 8 frames per cardiac cycle, and cardiac MRI. Left ventricular end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF) were obtained by analysing gated MPS data with four different programs: Quantitative Gated SPECT (QGS), GE MyoMetrix, Emory Cardiac Toolbox (ECT) and Exini heart.
RESULTS: All programs showed a mean bias of approximately −30 % for EDV, ESV and SV. The limits of agreement for ESV were double that of EDV and SV. Mean bias ± 2SD for EF (% of EF) was −9 ± 27 %, −15 ± 27 %, 6 ± 29 % and 0 ± 28 % for QGS, MyoMetrix, ECT and Exini, respectively (p< 0.05 for means, p= ns for SD, for all comparisons). See figure⇓.
CONCLUSION: Gated MPS, evaluated with four different programs, systematically underestimates left ventricular volumes by approximately 30 % and shows a high variability, especially for ESV. For EF, the accuracy was better, with a mean bias between −15 % and 6 % of EF. The precision was equally limited for all programs. These findings should be considered in clinical practice, as they may affect the interpretation of clinical examinations.