Comparative Performance of 68Ga-FAPI-04 and 18F-FDG PET/CT in Ovarian Cancer: Focus on Peritoneal Carcinomatosis

Abstract To evaluate the diagnostic performance of 68Ga-FAPI-04 positron emission tomography/computed tomography (PET/CT) in ovarian cancer compared with 18F-FDG PET/CT, focusing on peritoneal carcinomatosis. Twelve patients with histologically confirmed ovarian cancer underwent both 68Ga-FAPI-04 and 18F-FDG PET/CT within 1 week for staging, restaging, or recurrence assessment. SUVmax values of primary tumors, lymph nodes, and peritoneal metastases were compared. Tumor-to-background ratios were calculated, and statistical analyses were performed using nonparametric tests with p <0.05 considered significant. High-grade serous carcinoma was the predominant histology (83.3%). Lymph node metastases were detected in 7/12 patients (58.3%), including distant nodes in 3/12 (25.0%), locoregional nodes in 2/12 (16.7%), and combined disease in 2/12 (16.7%). Peritoneal carcinomatosis was observed in 9/12 patients (75.0%), with significantly higher SUVmax on 68Ga-FAPI-04 compared with 18F-FDG (19.17 ± 9.13 vs. 12.41 ± 7.13, p = 0.016). No significant differences were observed in nodal metastases or distant sites. In 4 of 12 patients (33.3%), 68Ga-FAPI-04 PET/CT identified additional lesions not visualized on 18F-FDG PET/CT. 68Ga-FAPI-04 PET/CT demonstrated superior peritoneal carcinomatosis detection compared with 18F-FDG PET/CT in ovarian cancer. Although derived from a small single-center cohort, these findings are consistent with emerging evidence and highlight the potential role of FAPI imaging in improving staging and management.