Clinical Meaning of 18 F-FDG PET/CT Incidental Gynecological Uptake: An 8-Year Retrospective Analysis

Objective Incidentalomas in 18 F-FDG PET/CT scan are a real and known challenge in oncological physician work, and to establish the nature of incidental findings is mandatory for subsequent clinical decision. The aim of this study is to evaluate the prevalence and the clinical significance of 18 F-FDG PET/CT gynecological incidental uptake. Materials and Methods We have retrospectively evaluated 11,000 women who underwent 18 F-FDG PET/CT from January 2008 to December 2015. The PET images were analyzed qualitatively, and the value of maximum standardized uptake value (SUV max ) was measured for the semi-quantitative analysis. Second imaging or histological examination was performed to obtain the final diagnosis. Results Unexpected FDG uptake in female reproductive organs was found in 125 (1.1%) 18F-FDG PET scan performed in 125 different women. 70 focal uptake was in reported in uterus, 33 in ovaries and 13 in both sites. In 64 patients, gynecological uptake was judged as physiological, in 41 as indeterminate and in 20 as malignant. After subsequent follow-up, 13 incidentalomas were classified as malignant, 19 as benign and 93 as physiological. Average SUV max in malignant lesions was significantly higher than non-malignant (19.64 vs 6.91; p < 0.01), and ROC analysis shows a cutoff value of 8.4 with a sensitivity of 100% and specificity of 77%. No patients with uptake judged as physiological found malignancy after follow-up exams. Eleven of the 13 malignancies were found in the 25 women in menopause. Conclusion 18 F-FDG gynecological uptake can have many different meanings: a correct anamnesis, related to the PET images, could be useful in characterization of physiological uptake. SUV max was significantly higher in malignant lesion, and incidental findings in menopause have a higher probability of malignancy.