The aim of this study was to assess the value of the cavity-to-myocardium count ratio (C/M ratio) calculated in resting 99mTc-sestamibi SPECT images to identify patients with depressed left ventricular ejection fraction (LVEF).
Methods: In the 95 patients studied, the C/M ratio was calculated from the midventricular short-axis slice using regions of interest drawn in the center of the cavity and in the most active area of the ventricular wall; its value was compared with LVEF measured using two-dimensional echocardiography.
Results: The C/M ratio correlated with LVEF (r = 0.6, p < 0.000001) and was significantly lower in patients with abnormal LVEF than those with normal LVEF: 0.026 +/- 0.028 versus 0.125 +/- 0.093, p < 0.000001. In the entire patient population, a C/M ratio < 0.07 identified the patients with depressed LVEF with a 94% sensitivity, 71% specificity and 82% accuracy.
Conclusion: The resting 99mTc-sestamibi C/M ratio is a useful parameter in identifying patients with depressed LVEF directly from the SPECT perfusion images.