Purpose. Assessment of blood flow and metabolism in the right ventricular myocardium in CTEPH by cardiac PET/CT and study of the correlation between PET parameters and other functional and hemodynamic data, which obtained with traditionally used techniques in patients with this pathology.

Materials and methods. 25 patients with proven CTEPH were included in the study; all patients underwent examinations according to a standard diagnostic protocol. As a part of scientific project, they underwent cardiac PET/CT studies with two radiopharmaceuticals: with [18F]-FDG to study the metabolism of the ventricular myocardium and with [13N]-NH3 to assess cardiac perfusion. The control group was presented by 23 patients with coronary artery disease without pulmonary hypertension, who had previously undergone PET for the underlying disease. Semi-quantitative accumulation indices (SUVs) and their ratio in the right and left ventricles (SUV RV/SUV LV) were obtained for each radioligand.

Results. The level of [18F]-FDG accumulation in the right ventricular myocardium in CTEPH was significantly higher than in the control group (p <0,001). In the CTEPH group, patients with low cardiac index (CI) had higher rates of [18F]-FDG uptake in the right ventricle relative to the left (p = 0,008) and higher accumulation of [13N]-NH3 in the lung parenchyma (p = 0,024) compared to patients with CI>2 L/min/m2. There was a statistically significant correlation between the levels of [18F]-FDG accumulation in the heart and main echocardiographic, hemodynamic, laboratory and clinical parameters. A significant correlation was also found between the rates of [13N]-NH3 accumulation and instrumental data (ECHO, RHC).

Discussion. The results confirm the glucose hypermetabolism in the right ventricular cardiomyocytes due to increase of anaerobic glycolysis during the development of pulmonary hypertension. This study demonstrated a reliable correlation between the uptake levels of [18F]-FDG and [13N]-NH3 in the heart and the results of other examinations, used to determine the severity of the disease and prognosis in CTEPH.

Conclusion. PET/CT should be considered as an effective noninvasive diagnostic modality that can be used in the assessment of right ventricular myocardium blood flow and metabolism as diagnostic indicators of disease severity in CTEPH.