Influence of different time framings, reconstruction algorithms and post-processing methods on the quantification of myocardial blood flow from ¹³N-NH₃ PET images

Background: The aim was to investigate to what extent the quantification of myocardial blood flow (MBF) from dynamic N-13-NH3 positron emission tomography (PET) images is affected by time frame schemes, time-of-flight (ToF), reconstruction algorithms, blood pool volume of interest (VOI) locations and compartment models in patients with suspected chronic coronary syndrome.Methods: A standard MBF value was determined from 25 patients' rest/stress N-13-NH3 PET/CT images reconstructed with ordered subset expectation maximization (OSEM), 5 s time frame for the first frames without ToF, subsequently analyzed using a basal VOI and the deGrado compartment model. MBFs calculated using 2 or 10 s for the first frames, ToF, block-sequential regularized expectation maximization (BSREM), apical or large VOI, Hutchins or Krivokapich compartment models were compared to MBFstandard in Bland-Altman plots (bias +/- SD).Results: Good agreement in global rest/stress MBF (mL/min/g) was found when changing the time frame scheme or reconstruction algorithm (MBFstandard vs. MBF2s: -0.02 +/- 0.06; MBF10s: 0.01 +/- 0.07; MBFBSREM: 0.01 +/- 0.07), while a lower level of agreement was found when altering the other factors (MBFstandard vs. MBFToF: -0.07 +/- 0.10; MBFapical VOI: -0.27 +/- 0.25; MBFlarge VOI: -0.11 +/- 0.10; MBFHutchins: -0.08 +/- 0.10; MBFKrivokapich: -0.47 +/- 0.50).Conclusions: Quantification of MBF from N-13-NH3 PET images is more affected by choice of compartment models, ToF and blood pool VOIs than by different time frame schemes and reconstruction algorithms.