Purpose. To assess the myocardial blood flow and coronary flow reserve in patients with multivessel coronary artery disease (MVCAD) by dynamic SPECT on cadmium-zinc-telluride (CZT) gamma camera. 
Material and methods. 70 patients were prospectively enrolled (52 men; 18 women). According to quantitative coronary angiography data all patients were divided into two groups:  1) multivessel coronary artery disease (CAD): 12 patients with two-vessel disease;  24 patients with three-vessel disease; 2) non multivessel CAD: 22 patients with nonobstructive disease; 12 patients with one vessel disease. The stenosis more than 50% in the left main trunk and more than 70 in major coronary vessels were considered as significant.  Within one week all patients underwent the assessment of myocardial blood flow (MBF) and coronary flow reserve (CFR) by dynamic 99mTc-Sestamibi CZT SPECT as well invasive fractional flow reserve assessment.  All scintigraphic images were acquired on the hybrid SPECT/CT unit (GE Discovery NM/CT 570C). The time-activity curves for the input function and whole left ventricular myocardium as well as for the LAD, LCx and RCA vessel territories were generated. The final stress and rest MBF values were calculated using a Net Retention flow model.The value of CFR was calculated as MBF ratio. Additionally, flow difference (FD) as the stress MBF minis the rest MBF was calculated.

Results. The values of SSS  were significantly (p< 0.01) different in multivessel CAD and nonmultivessel group patients: 5 (IQR 3; 8) and 3 (IQR 2; 4), respectively. SDS did not differ significantly in in these two groups: 3.0(IQR 1.0;5.0) and  2.0(IQR 1.0;3.0). The values of global stress MBF, CFR and FD were significantly (p<0.01) lower in patients with multivessel disease than in non multivessel CAD group: 0.49 ml/g/min (1.2; 0.64) vs 0.73 ml/g/min (0.56; 0.89); 1.42 (1.05; 1.83) vs 1.82 (1.59; 2.2); 0.1 ml/g/min (0.01; 0.27) vs 0.32 ml/g/min (0.45; 0.94), respectively. The significant correlations between coronary artery stenosis severity and the CZT-derived indexes were revealed: r= -0.46 for stress MBF; r= -0.28 for CFR and r= -0.37 for FD. According to the ROC analysis CZT-derived absolute stress MBF, CFR and FD demonstrated higher sensitivity in detection of multivessel disease in comparison with standard MPI indexes (SSS and SDS). The global CFR = 1.57 allows to identify MVCAD with a sensitivity and specificity 61.1% and 76.7%.

Conclusion. Our results found out that dynamic SPECT indexes have higher sensitivity than standard MPI in the detection of ischemia in patients with multivessel CAD. Absolute myocardial blood flow indexes derived by CZT could be useful in clinical practice in the management of patients with multivessel CAD.