Consistent tracer administration profile improves test–retest repeatability of myocardial blood flow quantification with (82)Rb dynamic PET imaging

OBJECTIVES: Quantification of myocardial blood flow (MBF) and stress/rest flow reserve is used increasingly to diagnose multi-vessel coronary artery disease and micro-vascular disease with PET imaging. However, variability in the measurements may limit physician confidence to direct revascularization therapies based on specific threshold values. This study evaluated the effects of rubidium-82 ((82)Rb) tracer injection profile using a constant-activity-rate (CA) vs a constant-flow-rate (CF) infusion to improve test–retest repeatability of MBF measurements. METHOD: 22 participants underwent single-session (82)Rb dynamic PET imaging during rest and dipyridamole stress using one of 2 test–retest infusion protocols: CA–CA (n = 12) or CA–CF (n = 10). MBF was quantified using a single-tissue-compartment model (1TCM) and a simplified retention model (SRM). Non-parametric test–retest repeatability coefficients (RPC(np)) were compared between groups. Myocardium-to-blood contrast and signal-to-noise ratios of the late uptake images (2 to 6 minutes) were also compared to evaluate standard myocardial perfusion image (MPI) quality. RESULTS: MBF values in the CA–CA group were more repeatable (smaller RPC(np)) than the CA–CF group using the 1TCM at rest alone, rest and stress combined, and stress/rest reserve (21% vs 36%, 16% vs 19%, and 20% vs 27%, P < 0.05, respectively), and using the SRM at Rest and Stress alone, Rest and Stress combined, and stress/rest reserve (21% vs 38%, 15% vs 25%, 22% vs 38%, and 23% vs 49%, P < 0.05, respectively). In terms of image quality, myocardium-to-blood contrast and signal-to-noise ratios were not significantly different between groups. CONCLUSIONS: Constant-activity-rate ‘square-wave’ infusion of (82)Rb produces more repeatable tracer injection profiles and decreases the test–retest variability of MBF measurements, when compared to a constant-flow-rate ‘bolus’ administration of (82)Rb, especially with SRM, and without compromising standard MPI quality. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s12350-016-0698-6) contains supplementary material, which is available to authorized users.