Patients with epithelial ovarian cancer who are scheduled for surgical intervention will be recruited in this study. They will undergo a comparative 68Ga-FAPI-04 and 18F-FDG PET/CT study before the surgery. No tumor-specific treatment is allowed between the scan and surgery, e.g. adjuvant chemotherapy, neoadjuvant chemotherapy, and intraperitoneal chemotherapy. Three types of lesions will be marked based on 68Ga-FAPI-04 and 18F-FDG PET/CT findings, which is FAPI+/FDG-, FAPI-/FAPI+, and FAPI+/FDG+ lesions. The marked lesions will be explored by the surgeon, resected if possible, and compared with histological results. A fourth type of lesion will be added into the analysis if that lesion is both FAPI and FAP negative but is a histological-confirmed positive lesion.