Detection of Functional Significance of Coronary Stenoses Using Dynamic 13N-Ammonia Stress-PET/CT with Absolute Values of Myocardial Blood Flow and Coronary Flow Reserve

Objectives. The aim of the study was to compare the values of myocardial blood flow (MBF) at stress, MBF at rest and coronary flow reserve (CFR) obtained by 13Nammonia stress-PET/CT in patients with various degrees of coronary stenosis and in healthy patients. And thus to estimate the possible contribution of the stress-PET/CT quantitative data to the detection of functionally significant coronary stenoses in patients with coronary artery disease (CAD). Materials and methods. 63 patients (mean age 64±9 years) with known CAD underwent dynamic 13N-ammonia stress-PET/CT followed by calculation of MBF both at stress and at rest in absolute units and CFR. We compared quantitative values in two groups of patients with coronary artery stenosis: 1) ≥75% (n = 36) and 2) <75% (n = 27) confirmed by invasive coronary angiography and in group of healthy patients (n = 11). Results. MBF at stress was significantly lower in group with ≥75% diameter stenoses (median 1,44 [1,21; 1,85] mL/min per g) compared with group with <75% diameter stenoses (2,42 [1,75; 2,89] mL/min/g) and the normal group (2,54 [2,31; 2,86] mL/min/g), (p <0,001). There was no reliable difference in MBF at rest between the three groups (p = NS). CFR was significantly lower in the group of patients with severe ≥75% stenoses (1,85 [1,54; 2,31]) in comparison with patients group with stenoses of intermediate <75% severity (2,73 [2,19; 3,21]), and also in comparison with the normal group (3,12 [2,75; 3,23]), (p <0,001). Conclusion. The values of MBF at stress and CFR are significantly lower in patients with severe coronary arteries stenoses comparing with the group of patients with mild and moderate stenoses. The value of MBF at rest used independently has no diagnostic utility for detection of functional significance of coronary artery stenoses. Keywords: myocardial blood flow, coronary flow reserve, PET/CT, 13N-ammonia, coronary stenosis