FIGURE 2. Comparison of mean LAD/LCx defect count ratio obtained from background-subtracted in vivo images. Transmural myocardial blood flow ratio at time when ^99mTc-N-NOET was administered during vasodilator stress is superimposed for comparison. Note that initial and 60-min delayed defect count ratios were significantly less in group 2 dogs with residual stenoses than those in group 1 dogs with no stenoses, reflecting greater diminution in coronary flow reserve preserved in group 2 dogs. *P < 0.05 vs. injection flow ratio; P < 0.01 vs. group 1; P < 0.05 vs. initial image.