Introduction/Background The objectives are to compare the efficacy between preoperative PET/CT and CeCT findings according with the surgical findings in patients that underwent surgery for epithelial ovarian cancer treatment and to evaluate the correlation between preoperative PCI calculated in both PET/CT an CeCT with surgery.

Methodology Retrospective unicentric observational study reviewing data of 30 patients diagnosed with epithelial ovarian cancer (primary or recurrence) and operated between July 2018-February 2021 in Clinica Universidad de Navarra. Every patient underwent PET/CT and CeCT. PET/CT was independently evaluated by a nuclear medicine doctor (PET-CT) and CeCT by an expert radiologist in gynecologic malignancies.PCI in surgery was calculated by two different gynecologic oncologists. If there was any discordance between them, a media between both scores was applied.Medical history and demographic data, preoperative FIGO stage, PET/CT findings, CT findings final pathology diagnosis, type of surgery and perioperative details were reviewed. Intraclass correlation coefficient was calculated to compare the PCI obtained preoperatively in PET/CT and CeCT to the PCI obtained in the final surgery.

Results The interclass correlation coefficient in the global cohort of patients compared to the PCI calculated intraoperatively was 0.867 for CeCT and 0.807 for PET-CT.Regarding the prediction of complete cytoreduction, the area under the curve in the CeCT was 0.659 and 0.690 in the PET-CT.

Conclusion Despite the small sample size, this initial study highlights that CeCT is more effective in calculating PCI preoperatively, however, PET-CT is better at predicting complete cytoreduction. Further validation in larger series is needed.