18F-FACBC compared with 11C-choline PET/CT in patients with biochemical relapse after radical prostatectomy: a prospective study in 28 patients

Introduction: The aim of our study was to compare the detection rate of anti-3-18F-FACBC PET/CT in comparison with 11C-choline PET/CT in the evaluation of disease recurrence of PCa after radical prostatectomy.

Patients and methods: Twenty-eight consecutive patients with biochemical relapse after radical prostatectomy were submitted to anti-3-18F-FACBC PET/CT and 11C-choline PET/CT to evaluate the site of disease recurrence. Androgen deprivation therapy was avoided in all cases. The primary end point was the overall detection rate of the 2 radiotracers. A patient-based analysis and a lesion-based analysis was performed. The target to background ratio (TBR) of each lesion was reported.

Results: At the time of PET scan, mean age was 67 years and mean prostate specific antigen (PSA) relapse was 2.9 ng/mL (range: 0.2-14.6). In patient-based analyses, 11C-choline PET/CT was positive in 5 patients and negative in 23 (detection rate = 17.8%) and anti-3-18F-FACBC PET/CT was positive in 10 patients and negative in 18 (detection rate = 35.7%). All lesions that were positive using 11C-choline were positive using anti-3-18F-FACBC PET/CT but with the latter radiotracer, 11 (61.1%) additional tumors were identified including 5 (17.8%) additional patients. The TBR of anti-3-18F-FACBC was greater than 11C-choline in 15 of 18 lesions, confirming a better image quality and contrast.

Conclusion: This preliminary study demonstrated that the detection rate of anti-3-18F-FACBC PET/CT is greater in comparison with 11C-choline, with approximately 20% of additional patients and approximately 60% additional lesions detected. Further studies, however, are required to assess the exact added value of this new tracer.