“…Subsequent studies compared the QGS results with other reference techniques, such as equilibrium radionuclide angiocardiography (ERNA), echocardiography, contrast ventriculography and magnetic resonance imaging [16, 19-21, 23, 26-36, 55]. The Emory Cardiac Toolbox (ECTb, Emory University, Atlanta, GA) has also been extensively validated by comparison with first-pass radionuclide ventriculography, ERNA, echocardiography and magnetic resonance imaging [23,25,30,34,55]. Furthermore, comparative studies with ERNA and magnetic resonance imaging have confirmed the reliability of 4D-MSPECT (University of Michigan Medical Center, Ann Arbor, MI) [32,34,55,56].…”