We performed a work-up study of cancer patients with incidentally found uncharacterized prostatic fluorine-18-fluorodeoxyglucose (18F-FDG) uptake in 18F-FDG PET/CT results. Then, we evaluated the clinical significance of the incidental prostate 18F-FDG uptake (IPU) in nonmalignant prostate tissues.Patients and methods
Overall, 51 men agreed to a physical prostate examination and an expressed prostatic secretion (EPS) test within 2 weeks after torso 18F-FDG PET/CT scans. We then reviewed the 18F-FDG PET/CT scans of the enrolled patients and evaluated the relationship between the 18F-FDG PET/CT, prostate-specific antigen, and prostatic laboratory findings.Results
The pathological diagnosis of five men indicated the presence of prostate cancer, and of the remaining 46 men, 27 cases showed IPU in the 18F-FDG PET/CT whereas 19 did not. The characteristics of the enrolled patients were as follows: mean age of 61.15±13.79 years (range: 30–83 years), maximum standardized uptake value of 2.64±1.33 (range: 1.2–7.1), and prostate-specific antigen of 3.10±3.50 ng/ml (range: 0.16–13.55 ng/ml). Ten of the 27 (37%) patients with IPU in the PET/CT scan showed bacterial infections in their prostate. A multivariate analysis indicated that the bacterial presence in the EPS increased the risk of IPU (adjusted odds ratio: 9.167; P=0.019).Conclusion
Bacterial presence in the prostate tends to increase the likelihood of IPU in 18F-FDG PET/CT scans. Therefore, men with incidental prostate 18F-FDG uptake should be considered for a possible prostate infection in addition to a concomitant malignancy.