Primal analysis of physiological 18F-FDG uptake in the endometrium of women

Objectives The objective of the study was to detect the characterize of physiological endometrium FDG uptake in women on PET/CT imaging.

Methods We reviewed retrospective 367 women who underwent PET/CT imaging in the PET/CT center during June 2006 to May 2008. The results were analyzed with menstrual state. 175 women who underwent PET/CT imaging for ealth examination and 192 patients who had no known gynecologic malignancy were included in the study.

Results 18 women (age 40.9 +/-5.3 years, range 30-51 years) showed physiological endometrium FDG uptake. 17 of them were reproductive age. It made up 10.3 per cent of total reproductive age women (168 cases) and 88.2% of them were in ovulatory and menstrual phase of menstrual cycle. Remnant one was 51 year old and had menopause for five months. The characteristics of endometrial foci increased FDG uptake showed as the inverted cone-shape or ovoid shape and located at the cavity of uterus. The standardized uptake value (SUV) of focal functioning FDG uptake showed as 3.95 ± 1.14. 10 of them had delayed imaging 3 hours after injection. Compared with the imaging 1 hour after injection, the SUV increased in 5 cases in the delayed imaging (average increased 25.3% ±17.8%, range 8.3%-52.4%), and decreased in 4 cases (average decreased 20.3% ±3.4%, range 12.8%-30.2%).

Conclusions Physiological FDG uptake was observed often in the endometrium of women of reproductive age. And it was more prominent in ovulatory and menstrual phase. The value of SUV in assessment physiological ovarian FDG uptake have to study further. It is therefore important to take a menstrual history and compare PET with pelvic CT imaging and sonography to distinguish physiological or benign causes from malignant uptake of endometrium.