Accumulation of [11C]acetate in normal prostate and benign prostatic hyperplasia: comparison with prostate cancer

Carbon-11 acetate positron emission tomography (PET) has been reported to be of clinical value for the diagnosis of prostate cancer. However, no detailed analysis has yet been carried out on the physiological accumulation of [(11)C]acetate in the prostate. The purpose of this study was to elucidate the physiological accumulation of [(11)C]acetate in the prostate using dynamic PET. The study included 30 subjects without prostate cancer [21 with normal prostate and nine with benign prostatic hyperplasia (BPH)] and six patients with prostate cancer. A dynamic PET study was performed for 20 min after intravenous administration of 555 MBq of [(11)C]acetate. The standardised uptake value (SUV) at 16-20 min post tracer administration and the early-to-late-activity ratio of the SUV (E/L ratio), which was determined by dividing the SUV(6-10 min) by the SUV(16-20min), were calculated to evaluate the accumulation of [(11)C]acetate. The prostate was clearly visualised and distinguished from adjacent organs in PET images in most of the cases. The SUV of the prostate (2.6+/-0.8) was significantly higher than that of the rectum (1.7+/-0.4) or bone marrow (1.3+/-0.3) ( P or =50 with normal prostate (0.98+/-0.04) or BPH (0.96+/-0.08) and patients with prostate cancer (1.02+/-0.12). In conclusion, a normal prostate exhibits age-related physiological accumulation of [(11)C]acetate. Careful interpretation of [(11)C]acetate PET images of prostate cancer is necessary because the SUV and the E/L ratio for the normal prostate and for BPH overlap significantly with those for prostate cancer.