[Evaluation of the ejection fraction tomoscintigraphy synchronised with an electrocardiogram].

Electrocardiographic gated myocardial scintigraphy (gated SPECT) allows simultaneous evaluation of left ventricular perfusion and contractility. The aim of this study was to assess the impact of the type of tracer and temporal sampling on the measurement of the ejection fraction by gated SPECT. Eighty-six consecutive patients (59 men, 27 women, average age 62 +/- 11 years) with a history of myocardial infarction (anterior N = 50--inferior N = 36) were studied. All had measurement of the isotopic ejection fraction by equilibrium angioscintigraphy and by gated SPECT sampled at 8 (N = 45, 52%) or 16 images/cycle RR (N = 41, 48%). After filtered retroprojection, the ejection fraction was calculated by a validated method (QGS). A better correlation between gated SPECT and equilibrium angioscintigraphy was observed at 16 images/cycle (r = 0.90) compared with 8 (r = 0.80). The Bland-Altman curves showed improved accuracy of the measurement of the ejection fraction by gated SPECT with 16 compared with 8 images/cycles sampling (mean differences of 0.37 +/- 6.06% and 4.3 +/- 7.71%, respectively). Multivariable analysis showed that temporary sampling was the only parameter to significantly affect the difference between the two methods. There was no difference between the use of Thallium and that of 99mTc-sestamibi. Gated SPECT, therefore, provides an accurate measurement of the ejection fraction for routine clinical usage, providing the acquisition is made at 16 images/cycle.