18 F-FDG PET/CT use in functional assessment of the testes: A systematic review.

Introduction: Our study analysed previous studies employing positron emission tomography with co-registered computer tomography (PET/CT) in andrological patient evaluation and assessed the differences in 2-[ ¹⁸ F]F-fluoro-2'-deoxyglucose (FDG) uptake between three groups: healthy testes, benign and malignant testicular pathology.
Methods: Medline and Embase were systematically searched for studies involving FDG-PET/CT imaging of testes with results expressed as mean standardised uptake value (SUV _mean ). A one-way ANOVA was used to compare SUV _mean between three groups. All papers assessing andrological parameters were pooled to compare fertility data.
Results: Seventeen studies, including three relating to fertility diagnosis, with a total of 830 patients, were included in the review. One-way ANOVA showed a statistical difference between mean values of tracer SUV _mean in healthy and malignant testes (Dif. = -2.77, 95% CI = -4.32 to 1.21, p < 0.01) as well as benign and malignant (Dif. = -2.95, 95% CI = -4.33 to -1.21, p < 0.01) but no difference between healthy and benign (Dif. = 0.19, 95% CI = -0.96 to 1.33, p = 0.90). There is some evidence to suggest that FDG uptake and testicular volume are positively correlated to total sperm count, sperm concentration and sperm motility and that germ cells are likely to account for the majority of testicular FDG accumulation.
Conclusion: Our findings indicate that malignant testicular lesions demonstrate a significantly higher FDG uptake than benign testicular lesions or healthy testes. Some evidence also suggests that FDG-PET could visualise metabolic activity and thus spermatogenesis; however more studies are required to determine whether FDG-PET could also be used to diagnose infertility. Further studies should focus on correlating both sex hormone-serum levels and semen analysis results with imaging data.
(© 2021 The Authors. Andrology published by Wiley Periodicals LLC on behalf of American Society of Andrology and European Academy of Andrology.)