Comparison of two three-dimensional gated SPECT methods with thallium in patients with large myocardial infarction

Background. Two different commercially available gated single photon emissi on computed tomography (GSPECT) methods were compared in a population of pa tients with a major myocardial infarction, Methods. Rest thallium GSPECT mas performed with a 90-degree dual-detector camera, 4 hours after injection of thallium-201 (Tl-201; 185 MBq) in 43 pat ients (mean age, 62 +/- 12 years) with a large myocardial infarction (mean defect size, 33% +/- 16%). End-diastolic volume (EDV), end-systolic volume (ESV), and left ventricular ejection fraction (LVEF) were calculated by usi ng QGS (Cedars Sinai) and MultiDim (Sopha Medical Vision International, Buc , France), Images were reconstructed by using a 2.5 zoom and a Butterworth filter (order, 5; cut-off frequency, 0.20), LVEF was calculated in all pati ents by using equilibrium radionuclide angiocardiography (ERNA), EDV, ESV, and LVEF were also measured by using left ventriculography (LVG). Results. Compared with LVG, QGS underestimated LVEF by means of an underest imation of mean EDV. MultiDim overestimated EDV and ESV. GSPECT EDV and ESV overestimation was demonstrated by means of Bland-Altman analysis to incre ase with left ventricular volume size (P < .05). The difference between LVG and GSPECT volumes was demonstrated by means of regression analysis to be correlated with infarction size. This effect was particularly important wit h MultiDim (P < .0001), Conclusion. In Tl-201 GSPECT, LVEF and volume measurements will vary accord ing to the type of software used.