PET/CT with 18F-choline after radical prostatectomy in patients with PSA <=2 ng/ml. Can PSA velocity and PSA doubling time help in patient selection?

PURPOSE: To investigate the performance of 18F-fluorocholine (18F-FCH) PET/CT in relation to the prostate-specific antigen (PSA) kinetic indexes, PSA doubling time (PSAdt) and PSA velocity (PSAve), in detecting recurrent prostate cancer (PC) in a selected population of patients treated with radical prostatectomy and with PSA <=2 ng/ml. METHODS: The study group comprised 79 patients (mean age 70 ± 7 years, range 58 - 77 years) who had been treated with radical surgery 30 to 90 months previously and with biochemical failure (defined as a measurable serum PSA level) who were evaluated with 18F-FCH PET/CT. In order to establish the optimal threshold for PSAdt and PSAve, the diagnostic performance of PSA, PSAdt and PSAve were compared by receiver operating characteristic analysis. RESULTS: In the population examined, PSA (mean ± SD) was 1.37 ± 0.44 ng/ml (range 0.21 - 2 ng/ml) before PET/CT examination, PSAdt was 10.04 ± 16.67 months and PSAve was 2.75 ± 3.11 ng/ml per year. 18F-FCH PET/CT was positive in 44 patients (55 %). PSAve and PSAdt were significantly different between patients with a positive and a negative 18F-FCH PET/CT scan. Thresholds of 6 months for PSAdt and 1 ng/ml per year for PSAve were selected. For PSAdt <=6 months the detection rate (DR) was 65 %, and for PSAve >1 ng/ml per year the DR was 67 %. PSA values were not significantly different between patients with a positive and a negative PET/CT scan. CONCLUSION: The results of our study suggest that 18F-FCH PET/CT could be considered for the evaluation of patients with biochemical recurrence of PC and with low PSA levels. Fast PSA kinetics could be useful in the selection of these patients.