Non-invasive cardiovascular imaging plays an important role in examination of patients with chronic coronary syndrome. Positron emission tomography (PET) has the highest diagnostic accuracy and prognostic significance due to the ability to assess myocardial blood flow (MBF) and coronary flow reserve (CFR). These physiological processes provide myocardial oxygen demand, both at rest and stress, as well as maintaining sufficient myocardial circulation during coronary artery constriction. At the same time, the high cost and low availability of assessing MBF and CFR by PET do not allow widespread use of this approach in clinical practice. The use of modern gamma cameras with cadmium zinc telluride detectors can be an alternative to PET. The aim of the review is to present fundamental information about MBF and CFR, as well as about the possibilities of using scintigraphy for determination of these parameters and their clinical significance.

Aim: To study the relationship of microcirculatory changes in coronary bed and electrocardiographic and laboratory signs of damage to myocardium in patients with acute myocardial infarction (AMI).Methods. The observational study included patients with newly emerged AMI. Depending on the ECG changes, the patients were divided into two groups: 1) with ST segment elevation (n = 75) (STEMI) and 2) without ST segment elevation (n = 44) (NSTEMI). All patients underwent electrocardiography, analysis of biochemical markers of myocardial damage, dynamic single photon emission computed tomography (SPECT) and myocardial perfusion imaging.Results. The study included 119 patients (age 62.5 ± 10.4 years, 63% men). STEMI patients had heavier perfusion defects at rest, 5.00 (3.00;9.00) and 0.00 (0.00;1.00), and after pharmacological stress test, 7.00 (5.00;13.00) and 2.50 (0.00;5.00), also they had more reduced stress myocardial blood flow (MBF), 1.09 (0.83;1.59) and 1.67 (1.36;2.46) ml/min/g, flow difference (FD), 0.36 (0.01;0.72) and 1.14 (0.63;1.72) ml/min/g, and myocardial flow reserve (MFR), 1.78 (1.11;2.19) and 2.57 (2.13;3.31), according to compared to NSTEMI patients. Correlation analysis revealed significant relationships between stress MBF and CPK after 24 hours and 4 days: r = –0.34 and r = = –0.31, troponin I upon admission and after 24 hours – r = –0.4 and r = –0.3; MFR and FD and troponin I upon admission – r = –0.41 and r = –0.41.Conclusion. Quantitative parameters of myocardial perfusion determined by early dynamic myocardial SPECT are associated with electrocardiographic changes and biochemical markers of myocardial damage and allow an adequate assessment of the severity of the disease in patients with AMI.

(1) Background: The objective of this study was to determine the optimal post-processing model for dynamic cadmium–zinc–telluride single-photon emission computed tomography (CZT-SPECT). (2) Methods: A total of 235 patients who underwent diagnostic invasive coronary angiography within three months of the SPECT and those who had coronary computed tomography angiography (CCTA) before SPECT (within 3 months) were enrolled in this study. Each SPECT study was processed to obtain global and regional stress myocardial blood flow (sMBF), rest-MBF (rMBF), myocardial flow reserve (MFR) and flow difference (FD) estimates obtained with 1-tissue-compartment (1TCM) and net retention (NR) modes, both with and without attenuation correction. (3) Results: The use of AC led to significantly higher sMBF, rMBF and DF values obtained by 1TCM compared those values derived by 1TCM with NAC; the lowest values of stress MBF and rest MBF were obtained by 1TCM_NAC. The resting flow, MFR and DF were significantly (p < 0.005) higher in the AC model than in NAC. All quantitative variables were significantly (p < 0.05) higher in NR_NAC than in the 1TC_NAC model. Finally, sMBF, rMBF and FD showed significantly (p < 0.05) higher values by using 1TMC_AC compared to NR_AC. (4) Conclusions: We suggested that 1-compartment and net retention models correctly reflect coronary microcirculation and can be used for clinical practice for evaluating quantitative myocardial perfusion by dynamic SPECT. Attenuation correction is an important step in post-processing dynamic SPECT data, which increases the consistency and diagnostic accuracy of models.

Non-obstructive coronary artery disease is generally considered as a favorable type of pathology, however, a number of studies indicate that in non-obstructive atherosclerosis, the risk of such cardiovascular events as myocardial infarction, ischemic stroke, sudden cardiac death and decompensated heart failure cannot be completely ruled out. This may be due to microvascular dysfunction. However, due to the small diameter of vessels, none of the imaging techniques used in clinical practice makes it possible to assess microvascular morphology. To date, the most well-established methods for assessing myocardial perfusion are single-photon emission computed tomography (SPECT) and positron emission tomography (PET). The ability to quantify myocardial blood flow and coronary flow reserve allows SPECT and PET to be the methods of choice for non-invasive diagnosis of microvascular dysfunction. This review is devoted to current data on the clinical significance of radionuclide diagnosis of microvascular dysfunction in patients with non-obstructive coronary artery disease.

Aim. To study the parameters of myocardial blood flow (MBF) and coronary flow reserve (CFR) in patients with heart failure (HF) with preserved ejection fraction and evaluate their relationship with the severity of HF.Material and methods. The study included 47 patients (men, 68,7%) aged 65,0 (58,0; 72,0) years with left ventricular ejection fraction of 62 (56; 67)% and coronary artery stenosis <50%. Serum levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) were assessed by enzyme immunoassay. MBF and CFR values were assessed using cardiac single photon emission computed tomography.Results. Depending on NT-proBNP levels, the patients were divided into 2 groups (p<0,001): the 1st group included (n=15) patients with NT-proBNP <125 pg/ml (58,2 [41,6; 70,7] pg/ml), while in the 2nd group (n=32) — with NT-proBNP ≥125 pg/ml (511,4 [249,8; 1578,1] pg/ml). The group of patients with high NTproBNP levels was characterized by higher values (by 33,8%, p=0,0001) of resting MBF and reduced CFR (by 14,7%, p=0,001) compared with patients with normal NT-proBNP level: resting MBF — 0,65 (0,44; 0,79) vs 0,43 (0,30; 0,58) ml/min/g; CFR — 2,21 (1,52; 2,83) vs 2,59 (2,47; 3,05), respectively. At the same time, MBF at stress did not differ between the groups. The relationship of NTproBNP levels with global CFR (p=0,012; r=-0,339) and MBF at rest (p=0,012; r=0,322) was established. A stepwise decrease in global CFR was revealed depending on the NYHA class as follows (p<0,001): 2,79 (2,52; 2,93); 1,8 (1,55; 2,08); 1,31 (1,23; 1,49) — for class I, II, and III, respectively.Conclusion. A decrease in CFR in patients with HF with preserved ejection fraction indicates impaired myocardial blood supply, which, in this group of patients, is associated with microcirculatory changes. At the same time, the severity of MBF alterations is closely related to HF severity.