Relationship Between Pharmacokinetic Parameters and Imaging Duration in Dynamic 11C-Acetate Cardiac PET/CT

Abstract

Objective To evaluate the effect of imaging time on the pharmacokinetic parameters calculation of dynamic 11C-acetate cardiac positron emission tomography (PET) scan and to investigate the feasibility of shortening the imaging time in clinical practice. Methods This study was a retrospective analysis and 46 subjects who underwent 11C-acetate PET/CT cardiac imaging at Peking Union Medical College Hospital (from a clinical study assessing myocardial tissue and metabolic characteristics in men with alcohol consumption) were included. Each subject was injected with 740 MBq 11C-acetate before a 40-minute PET/CT scan, and time-activity curve in the left ventricle was collected as input function. Pharmacokinetic parameters (K1 and k2) calculated from the 40-minute dynamic data (53 frames) was regarded as the reference standard. The number of included dynamic image frames was sequentially reduced from the last frame, and the corresponding pharmacokinetic parameters of 11C-acetate were calculated. Correlation, consistent analysis of trends and the relative differences on pharmacokinetic parameters between shortened data and reference standard were evaluated. The shortest acceptable scan time was determined based on the criterion that the R2 of linear regression models was higher than 0.9 in all myocardial segments. Results The R2 between 11C-acetate pharmacokinetic parameters and the reference standard was higher than 0.9 in all myocardial segments at scan time ≥17 min (37 frames) for both K1 and k2. The regression coefficients of K1 values calculated from the shortened data and the reference standard in myocardium were distributed in the range of 0.982-1.007, and the regression coefficients of k2 values calculated from the shortened data and the reference standard were distributed in the range of 0.783-1.000. When the scan time was reduced to 17 min (37 frames), the K1 and k2 values of left anterior descending branch, right coronary artery and left circumflex branch perfusion regions were significantly different from the reference standard (all P < 0.05). Left anterior descending branch perfusion region had the highest relative difference (RD) [K1: (3.93±1.98)%; k2: (13.79±6.40)%], while right coronary perfusion region had the lowest RD [K1: (2.84±1.89)%; k2: (9.74±5.62)%]. Conclusions For the male population with alcohol consumption or are healthy, shortening the scan time to 17 min (37 frames) during dynamic 11C-acetate PET/CT cardiac imaging can obtain tracer pharmacokinetic parameters consistent with the reference standard, which can provide references for optimizing clinical image acquisition time.

Keywords

• positron emission tomography
• 11c-acetate
• myocardial perfusion
• pharmacokinetic parameters
• one-tissue compartment model