Abstract
BACKGROUND: The quantification of myocardial blood flow (MBF) and coronary flow reserve (CFR) are useful approaches for evaluating the functional severity of coronary artery disease (CAD). (15)O-water positron emission tomography (PET) is considered the gold standard method for MBF quantification. However, MBF measurements in (15)O-water PET with three-dimensional (3D) data acquisition, attenuation correction using computed tomography (CT), and time of flight have not been investigated in detail or validated. We conducted this study to evaluate the diagnostic potential of MBF measurements using PET/CT for a comparison of a control group and patients suspected of having CAD. RESULTS: Twenty-four patients with known or suspected CAD and eight age-matched healthy volunteers underwent rest and pharmacological stress perfusion studies with (15)O-water PET/CT. The whole and three regional (left anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA) territory) MBF values were estimated. The CFR was computed as the ratio of the MBF during adenosine triphosphate-induced stress to the MBF at rest. The inter-observer variability was assessed by two independent observers. PET/CT using a (15)O-water dose of 500 MBq and 3D data acquisition showed good image quality. A strong inter-observer correlation was detected in both the whole MBF analysis and the regional analysis with high intra-class correlation coefficients (r > 0.90, p < 0.001). Regional MBF at rest (LAD, 0.82 ± 0.15 ml/min/g; LCX, 0.83 ± 0.17 ml/min/g; RCA, 0.71 ± 0.20 ml/min/g; p = 0.74), MBF at stress (LAD, 3.77 ± 1.00 ml/min/g; LCX, 3.56 ± 1.01 ml/min/g; RCA, 3.27 ± 1.04 ml/min/g; p = 0.62), and CFR (LAD, 4.64 ± 0.90; LCX, 4.30 ± 0.64; RCA, 4.64 ± 0.96; p = 0.66) of the healthy volunteers showed no significant difference among the three regions. The global CFR of the patients was significantly lower than that of the volunteers (2.75 ± 0.81 vs. 4.54 ± 0.66, p = 0.0002). The regional analysis of the patients demonstrated that the CFR tended to be lower in the stenotic region compared to the non-stenotic region (2.43 ± 0.81 vs. 2.95 ± 0.92, p = 0.052). CONCLUSIONS: (15)O-water PET/CT with 3D data acquisition can be reliably used for the quantification of functional MBF and CFR in CAD patients.