In 21 patients, the authors compared results with quantitative gated single photon emission computed tomography (SPECT) to results with magnetic resonance imaging in the assessment of left ventricular (LV) end-diastolic volume (LVEDV), end-systolic volume (LVESV), and ejection fraction (LVEF). Between the two methods, correlations were good for LVEF (r = 0.85), LVEDV (r = 0.94), and LVESV (r = 0.95). Quantitative gated SPECT can help determine LVEF, LVEDV, and LVESV.