Can we rely on 99Tcm-sestamibi gated tomographic myocardial perfusion imaging to quantify left ventricular function? A comparative study with classical isotopic techniques for the measurement of ejection fraction.

The assessment of left ventricular ejection fraction is an important element in the evaluation of cardiac performance, and one of the most commonly performed tests in nuclear cardiology. The aim of this study was to evaluate the accuracy and reliability of ejection fraction values calculated from ECG-gated myocardial perfusion single photon emission tomography (GSPET) in comparison with standard scintigraphic methods. Eight-frame gated SPET was recorded 60-90 min after the injection of 99Tcm-sestamibi at rest. The ejection fraction was calculated using a semi-automatic edge-detection technique based upon a threshold-searching method and compared with values obtained from first-pass (FPRNA) or equilibrium radionuclide angiography (ERNA) in 60 and 40 patients respectively with a broad range of ejection fraction values. Very good reproducibility was noted, with an inter- and intra-observer variability of -0.2 +/- 3.5% (range -7.6 to 6.9%, r = 0.97) and -0.2 +/- 2.2% (range -5.9 to 3.5%, r = 0.99) respectively. Similarly, a high concordance was found between GSPET and FPRNA and between GSPET and ERNA over the range of ejection fraction values (13 to 77%), the mean (+/-S.D.) difference being 0.8 +/- 3.8% (r = 0.97, P = N.S.) and 0.03 +/- 5.3% (r = 0.94, P = N.S.) respectively. Applying the Bland-Altman plot, no systematic bias of one method related to the other was observed, even at extreme ejection fraction values. Gated myocardial perfusion SPET with a 99Tcm tracer thus offers a unique opportunity to quantify cardiac performance and perfusion simultaneously and non-invasively.