The detection rate of [¹¹C]Choline-PET/CT depends on the serum PSA-value in patients with biochemical recurrence of prostate cancer

Purpose: An increase of the serum PSA-level is a sensitive in vitro marker for recurrent prostate cancer. However, it remains difficult to differentiate between local, regional or distant recurrent disease. The aim of this study was to assess the relationship between the detection rate of [¹¹C] Choline-PET/CT and the serum PSA-level in patients with a biochemical recurrence of prostate cancer with the view towards localisation of recurrent disease. Methods: Sixty-three patients (mean age, 68.8 ± 6.9; range, 45-83 years) with biochemical recurrence after primary therapy for prostate cancer were included in the analysis. Mean PSA-levels were 5.9 ± 9.7 ng/ml (range, 0.2-39 ng/ml; median, 2.15). Of the 63 patients, 17 were under anti-androgen therapy at the time of [¹¹C]Choline PET/CT. Patients underwent a [¹¹C]Choline-PET/CT study after injection of 656 ± 119 MBq [¹¹C]Choline on a Sensation 16 Biograph PET/CT scanner. Results: Of the 63 patients, 35 (56%) showed a pathological [¹¹C]Choline uptake. The detection rate of [¹¹C]Choline-PET/CT showed a relationship with the serum PSA-level: The detection rate was 36% for a PSA-value <1 ng/ml, 43% for a PSA-value 1-<2 ng/ml, 62% for a PSA-value 2-<3 ng/ml and 73% for a PSA-value ≥3 ng/ml. Anti-androgen therapy did not show a significant effect on the detection rate of [¹¹C]Choline-PET/CT (p = 0.374). Conclusion: As an important result our study shows that even for PSA-values <1.0 ng/ml the detection efficiency of [¹¹C]Choline-PET/CT is 36%. Furthermore, the detection rate of [¹¹C]Choline-PET/CT shows a positive relationship with serum PSA-levels in patients with biochemical recurrence of prostate cancer after primary therapy. Therefore, in these patients, [ ¹¹C]Choline PET/CT allows not only to diagnose but also to localise recurrent disease with implications on disease management (localised vs systemic therapy).