Quantification of myocardial blood flow with 82Rb positron emission tomography: clinical validation with 15O-water

Prior, John ; Allenbach, Gilles ; Valenta, Ines ; Kosinski, Marek ; Burger, Cyrill ; Verdun, Francis ; Bischof Delaloye, Angelika ; Kaufmann, Philipp

In: European Journal of Nuclear Medicine and Molecular Imaging, 2012, vol. 39, no. 6, p. 1037-1047

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    Summary
    Purpose: Quantification of myocardial blood flow (MBF) with generator-produced 82Rb is an attractive alternative for centres without an on-site cyclotron. Our aim was to validate 82Rb-measured MBF in relation to that measured using 15O-water, as a tracer 100% of which can be extracted from the circulation even at high flow rates, in healthy control subject and patients with mild coronary artery disease (CAD). Methods: MBF was measured at rest and during adenosine-induced hyperaemia with 82Rb and 15O-water PET in 33 participants (22 control subjects, aged 30 ± 13years; 11 CAD patients without transmural infarction, aged 60 ± 13years). A one-tissue compartment 82Rb model with ventricular spillover correction was used. The 82Rb flow-dependent extraction rate was derived from 15O-water measurements in a subset of 11 control subjects. Myocardial flow reserve (MFR) was defined as the hyperaemic/rest MBF. Pearson's correlation r, Bland-Altman 95% limits of agreement (LoA), and Lin's concordance correlation ρ c (measuring both precision and accuracy) were used. Results: Over the entire MBF range (0.66-4.7ml/min/g), concordance was excellent for MBF (r = 0.90, [82Rb-15O-water] mean difference ± SD = 0.04 ± 0.66ml/min/g, LoA = −1.26 to 1.33ml/min/g, ρ c = 0.88) and MFR (range 1.79-5.81, r = 0.83, mean difference = 0.14 ± 0.58, LoA = −0.99 to 1.28, ρ c = 0.82). Hyperaemic MBF was reduced in CAD patients compared with the subset of 11 control subjects (2.53 ± 0.74 vs. 3.62 ± 0.68ml/min/g, p = 0.002, for 15O-water; 2.53 ± 1.01 vs. 3.82 ± 1.21ml/min/g, p = 0.013, for 82Rb) and this was paralleled by a lower MFR (2.65 ± 0.62 vs. 3.79 ± 0.98, p = 0.004, for 15O-water; 2.85 ± 0.91 vs. 3.88 ± 0.91, p = 0.012, for 82Rb). Myocardial perfusion was homogeneous in 1,114 of 1,122 segments (99.3%) and there were no differences in MBF among the coronary artery territories (p > 0.31). Conclusion: Quantification of MBF with 82Rb with a newly derived correction for the nonlinear extraction function was validated against MBF measured using 15O-water in control subjects and patients with mild CAD, where it was found to be accurate at high flow rates. 82Rb-derived MBF estimates seem robust for clinical research, advancing a step further towards its implementation in clinical routine