Simulation of Low-Dose Protocols for Myocardial Perfusion ⁸²Rb Imaging

Quantification of myocardial perfusion and myocardial blood flow using ⁸²Rb PET is increasingly used for assessment of coronary artery disease. Current guidelines suggest injections of 1,100-1,500 MBq for both stress and rest. Reducing the injected dose avoids PET system saturation in first-pass flow images and reduces radiation exposure, but the impact on myocardial perfusion quantification of static perfusion images is not fully understood. In this study, we aimed to evaluate the feasibility of performing myocardial perfusion scans using either a half-dose (HfD) or quarter-dose (QD) protocol using reconstructions from acquired full-dose (FD) scans. Methods: This study comprised 171 patients who underwent rest/stress ⁸²Rb PET with a 3-dimensional 4-ring PET/CT scanner using a FD protocol and invasive coronary angiography within 6 mo of the PET emission scan. HfD and QD reconstructions were obtained using the prescribed percentage of events from the FD list-mode files. The total perfusion deficit was quantified for rest (rTPD), stress (sTPD), and ischemia (ITPD = sTPD - rTPD). Diagnostic accuracy for obstructive coronary artery disease, defined as at least 70% stenosis in any of the 3 major coronary arteries, was compared with area under the receiver-operating-characteristic curve (AUC). Results: Patients with a median body mass index of 28.0 (interquartile range, 23.9-31.7) were injected with doses of 1,165 ± 189 MBq of ⁸²Rb. For sTPD, FD and HfD protocols had similar AUCs (FD, 0.807; HfD, 0.802; P = 0.108), whereas QD had a reduced AUC (0.786, P = 0.037). There was no difference in the AUC obtained for ITPD among the 3 protocols (FD, 0.831; HfD, 0.835; QD, 0.831; all P ≥ 0.805). Conclusion: HfD imaging does not affect the quantitative diagnostic accuracy of ⁸²Rb PET on 3-dimensional PET/CT systems and could be used clinically.