PET MPI With F-18 FlurpiridazVersus Rb-82: Insights Into Blood Flow and Splenic Switch-Off

Background: F-18 flurpiridaz is a new, Food & Drug Administration–approved radiotracer for positron emission tomography (PET) myocardial perfusion imaging (MPI) with favorable physical properties and demonstrated superiority over single-photon emission computed tomography MPI in prior trials. However, no direct comparisons with the widely used rubidium-82 (Rb-82) tracer have been reported to date. Case Summary: We present the case of a 71-year-old man with coronary artery disease who underwent a clinically indicated Rb-82 PET MPI followed 2 weeks later by an F-18 flurpiridaz PET MPI for research purposes. Discussion: This case highlights the potential advantages of F-18 flurpiridaz. Compared with Rb-82 PET, the F-18 flurpiridaz PET demonstrated superior image quality, more pronounced splenic switch-off, and higher stress myocardial blood flow and myocardial flow reserve. These differences may be attributed to the shorter positron range, higher myocardial extraction fraction, and near-linear relationship with myocardial blood flow of F-18 flurpiridaz. Take-Home Messages: F-18 flurpiridaz PET MPI demonstrated superior image quality compared with Rb-82 PET MPI. Splenic switch-off was more visually and quantitatively pronounced with F-18 flurpiridaz, potentially improving the ability to distinguish responders to regadenoson from nonresponders. Stress myocardial blood flow and myocardial flow reserve were higher with F-18 flurpiridaz, in part owing to its higher myocardial extraction fraction.