Physiologic uptake of 18F-FDG in transposed ovaries may mimic metastasis on 18F-FDG PET/CT imaging

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Abstract

Background

Ovarian transposition is aimed at preserving ovarian function before irradiation in pelvic malignancies. The extrapelvic location of the ovaries and their physiologic fluorine-18-fluorodeoxyglucose (18F-FDG)-uptake is a potential source of misdiagnosis as metastasis on 18F-FDG PET/CT. We describe the 18F-FDG PET/CT characteristics of transposed ovaries and their changes over time.

Patients and methods

We reviewed 18F-FDG PET/CT studies of all consecutive women with pelvic malignancies who underwent ovarian transposition between 2007 and 2013. Studies were grouped according to the time period over which they were carried out. Findings were categorized by location, size, appearance (solid/mixed/cystic), presence of surgical clips, ovarian 18F-FDG uptake (maximum standardized uptake value), and attenuation values on CT (Hounsfield units). Group time-period differences were assessed.

Results

Seventy-nine 18F-FDG PET/CT studies were reviewed, 30 before and 49 after transposition. Time-period groups after transposition were up to 4 months (18 studies), 4.1–12 months (n=14), and more than 12 months (n=17). After transposition, ovaries were located mainly in the paracolic gutter (n=32) and subhepatic regions (n=18). Surgical clips were present in 67%. Both ovaries appeared more solid 1 year after surgery than preoperatively (13.7% before vs. 61.3% after surgery; P<0.001). Transient 18F-FDG-avidity was observed in 11 ovaries. Hounsfield unit values were higher within 4 months after surgery than preoperatively, reverting thereafter to preoperative values.

Conclusion

After ovarian transposition, nonanatomic location, loss of cysts formation in favor of solid appearance over time, and intermittent 18F-FDG uptake of functioning transposed ovaries might mimic metastatic lesions. Careful interpretation of 18F-FDG PET/CT findings is mandatory in women with pelvic malignancies who have undergone ovarian transposition.

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