Optimally Repeatable Kinetic Model Variant for Myocardial Blood Flow Measurements with Rb PET.

Myocardial blood flow (MBF) quantification with Rb positron emission tomography (PET) is gaining clinical adoption, but improvements in precision are desired. This study aims to identify analysis variants producing the most repeatable MBF measures. 12 volunteers underwent same-day test-retest rest and dipyridamole stress imaging with dynamic Rb PET, from which MBF was quantified using 1-tissue-compartment kinetic model variants: (1) blood-pool versus uptake region sampled input function (Blood/Uptake-ROI), (2) dual spillover correction (SOC-On/Off), (3) right blood correction (RBC-On/Off), (4) arterial blood transit delay (Delay-On/Off), and (5) distribution volume (DV) constraint (Global/Regional-DV). Repeatability of MBF, stress/rest myocardial flow reserve (MFR), and stress/rest MBF difference (ΔMBF) was assessed using nonparametric reproducibility coefficients (RPC = 1.45 × interquartile range). MBF using SOC-On, RVBC-Off, Blood-ROI, Global-DV, and Delay-Off was most repeatable for combined rest and stress: RPC = 0.21 mL/min/g (15.8%). Corresponding MFR and ΔMBF RPC were 0.42 (20.2%) and 0.24 mL/min/g (23.5%). MBF repeatability improved with SOC-On at stress ( < 0.001) and tended to improve with RBC-Off at both rest and stress ( < 0.08). DV and ROI did not significantly influence repeatability. The Delay-On model was overdetermined and did not reliably converge. MBF and MFR test-retest repeatability were the best with dual spillover correction, left atrium blood input function, and global DV.