Purpose. The purpose of this study was to determine and analyze the differences in the quantitative values of myocardial blood flow according to positron emission tomography combined with computed tomography (PET/CT) in groups of coronary arteries with different degrees of stenosis in patients with coronary artery disease (CAD).

Materials and Methods. 122 patients (102 with CAD, 20 – healthy) were examined. All patients underwent invasive coronary angiography and dynamic 13N-ammonia stress-PET/CT with the determination of the regional coronary flow reserve and myocardial blood flow. They were compared in the groups of arteries: 1) with severe coronary stenoses (75-100%, n = 99); 2) mild and moderate stenoses (50-74%, n = 101); 3) intact arteries in CAD group (stenoses 0-40%, n = 106); 4) healthy patients (n = 60).

Results. Coronary flow reserve and stress myocardial blood flow are significantly lower (p <0.001) in the group of arteries with stenoses ≥75% compared to all groups (2nd, 3rd and 4th). According to the same indicators, the groups of arteries with mild, moderate stenoses and intact arteries of patients with CAD did not differ (p >0.05). At the same time, the reserve and stress myocardial blood flow were significantly lower in the group of intact arteries of CAD patients compared to the intact arteries of healthy patients. The diagnostic value of coronary flow reserve in the detection of various gradations stenoses exceeded the diagnostic value of the stress myocardial blood flow. At the same time, the sensitivity, specificity and accuracy of the coronary flow reserve selectively for mild and moderate stenoses was 45%, 80% and 67%; for severe stenoses (75-100%) - 85%, 80% and 82%, respectively.

Conclusion. Regional quantitative indicators of myocardial blood flow and coronary flow reserve by stress-PET/CT are highly sensitive and specific for the detection of severe coronary stenoses. The suboptimal sensitivity and accuracy of the method in the detection of mild and moderate stenoses are presumably associated with a low proportion of hemodynamically significant changes in this group. In comparison with the arteries of healthy patients, lower values of myocardial blood flow and coronary flow reserve in the intact arteries of patients with CAD may be due to the presence of microvascular dysfunction.