Purpose: Changes in left ventricular (LV) ejection fraction (EF) seen in gated Rb data are of interest because the heart is in a genuinely different physiologic state during stress than at rest. A measure that validates internal consistency of LV EF data would be highly desirable. Left ventricular mass calculations are performed simultaneously with EF determinations, requiring similar operator choices, and although LV volumes may change from rest to stress, mass values should be constant. Constancy of LV mass calculations could provide a useful internal check on the consistency of LV EF computations.
Patients and methods: We retrospectively reviewed data for 205 patients referred for evaluation of known or suspected coronary disease who had rest and regadenoson stress gated Rb PET/CT myocardial perfusion imaging. Equilibrium gated myocardial perfusion PET data were analyzed to calculate LV volumes, EF, and simultaneously mass values.
Results: Rest mass ranged from 62 to 284 g (median, 115 g), stress mass from 39 to 315 g (median, 120 g), and differences were -25 to +25 g (median, 1 g). Rest and stress mass values were statistically similar (121 ± 37 g vs 124 ± 49 g, P = 0.45) and correlated strongly with one another (r = 0.94, P < 0.0001).
Conclusions: Left ventricular mass calculations are constant from rest to stress over a wide range of ventricular volumes and ejection fractions. Consistency of LV mass values can serve as confirmation of the appropriateness of operator choices when LV EF calculations are performed.