FIGURE 4. After dividing population into 5 subgroups according to ERNA range, we show that underestimation of LVEF by QGS at 20 min (A) and at 4 h (B) progressively increases when actual LVEF is high. Paired t tests are significant in groups with LVEF 
30%. MTK at 20 min (C) accurately measures LVEF with no significant differences between gated SPECT and ERNA values in all subgroups. Results obtained with MTK at 4 h (D) show similar progressive underestimation of LVEF 40%, as with QGS. Boxes represent mean underestimations with associated error bars.
