Quantitative and qualitative comparison of Rubidium-82 and Oxygen-15 water cardiac PET

Background: Differences in tracer characteristics may influence the interpretation of positron emission tomography myocardial perfusion imaging (MPI). We compare the reading of MPIs with a low-extraction retention tracer (Rb) and a high-extraction non-retention tracer (O-water) in a selected cohort of patients with known coronary artery disease (CAD). Methods: Thirty-nine patients with known CAD referred to Rb MPI due to angina underwent rest and stress imaging with both tracers and experienced MPI readers provided blinded consensus reads of all studies. In addition, a comparison of regional and global quantitative measures of perfusion was performed. Results: The results showed 74 % agreement in the reading of Rb and O-water MPI for regional reversible ischemia and global disease, and 82 % agreement for regional irreversible ischemia. The O-water MPI identified more cases of global disease (n = 12 (O-water) vs n = 4 (Rb), p = 0.03), whereas differences in reversible ischemia (n = 22 vs n = 16, p = 0.11) and, irreversible ischemia (n = 8 vs n = 11, p = 0.45) were not significant. The correlation between myocardial blood flow measured using the two tracers was similar to previous studies (R = 0.78) with wide limits of agreement (−0.93 to 0.84 ml/g/min). Conclusions: Agreement between consensus readings of Rb and O-water MPI was good in patients with known CAD. In this limited size study, no significant differences in the identification of reversible and irreversible ischemia found, whereas O-water MPI had a higher positive rate for suspected global disease.