Usefulness of FDG PET in the differential diagnosis of borderline ovarian tumors from early stage malignant ovarian tumors

Objectives Borderline ovarian tumors (BOT) have favorable clinical courses and good prognoses compared with malignant ovarian tumors (MOT). To differentiate BOT from early stage MOT (FIGO stage I and II), we quantitatively assessed the metabolic status of ovarian neoplasms using 18F-fluorodeoxyglucose (FDG) PET/CT.

Methods Among 71 patients who had preoperative FDG PET/CT due to ovarian neoplasms between July 2007 and April 2009, 15 patients with BOT or early stage MOT were included after pathological confirmation. For comparison between two groups, the longest diameter of each tumor was measured on CT or pelvic MRI, and maximum standardized uptake value (SUVmax) of the tumor was measured on FDG PET/CT, respectively.

Results The BOT group (n=7) consisted of 5 mucinous and 2 serous tumors, and the MOT group (n=8) was all epithelial ovarian tumors. No significant difference was found in age (48.9 ± 19.6 y vs. 56.9 ± 11.1 y) and tumor size (13.3 ±7.9 cm vs. 14.5 ± 8.6 cm) between the two groups. However, SUVmax of the BOT group was significantly lower than the early stage MOT group (3.1 ± 1.6 vs. 6.2 ± 2.5, p = 0.014). SUVmax of 3.5 was the best cut-off to differentiate BOT from MOT with a sensitivity of 71.4% and specificity of 87.5% by the ROC analysis (p = 0.001).

Conclusions We demonstrated that the metabolic status assessed by FDG PET/CT successfully differentiated BOT from MOT. Especially in the early stage without other findings favoring malignancy, FDG PET/CT could be useful for the differential diagnosis of ovarian neoplasm