11C-Choline Pharmacokinetics in Recurrent Prostate Cancer

The aim of this study was to investigate the value of pharmacokinetic modeling for quantifying 11C-choline uptake in patients with recurrent prostate cancer. Methods: In total, 194 patients with clinically suspected recurrence of prostate cancer underwent 11C-choline dynamic PET over the pelvic region (0-8 min), followed by a 6-min static acquisition at about 25 min after injection. Regions of interest were drawn over sites of disease identified by a radiologist with experience in nuclear medicine. 11C-choline uptake and pharmacokinetics were evaluated by SUV, graphical analysis (Patlak plot; Ki P), and 1-and 2-compartment pharmacokinetic models (K1, K1/k2, k3, k4, and the macro parameter Ki C). Twenty-four local recurrences, 65 metastatic lymph nodes, 19 osseous metastases, and 60 inflammatory lymph nodes were included in the analysis, which was subsequently repeated for regions of interest placed over the gluteus maximus muscle and adipose tissue as a control. Results: SUVmean and Ki P were 3.60 +/- 2.16 and 0.28 +/- 0.22 min(-1) in lesions, compared with 2.11 +/- 1.33 and 0.15 +/- 0.10 min(-1) in muscle and 0.26 +/- 0.07 and 0.02 +/- 0.01 min(-1) in adipose tissue. According to the Akaike information criterion, the 2-compartment irreversible model was most appropriate in 85% of lesions and resulted in a K1 of 0.79 +/- 0.98 min(-1) (range, 0.11-7.17 min(-1)), a K1/k2 of 2.92 +/- 3.52 (range, 0.31-20.00), a k3 of 0.36 +/- 0.30 min(-1) (range, 0.00(-1).00 min(-1)) and a Ki C of 0.28 +/- 0.22 min(-1) (range, 0.00-1.33 min(-1)). The Spearman. between SUV and Ki P, between SUV and Ki C, and between Ki P and Ki C was 0.94, 0.91, and 0.97, respectively, and that between SUV and K1, between SUV and K1/k2, and between SUV and k3 was 0.70, 0.44, and 0.33, respectively. Malignant lymph nodes exhibited a higher SUV, Ki P, and Ki C than benign lymph nodes. Conclusion: Although 11C-choline pharmacokinetic modeling has potential to uncouple the contributions of different processes leading to intracellular entrapment of 11C-choline, the high correlation between SUV and both Ki P and Ki C supports the use of simpler SUV methods to evaluate changes in 11C-choline uptake and metabolism for treatment monitoring.