[68Ga]Ga-FAPI-04 PET/CT in the evaluation of epithelial ovarian cancer: comparison with [18F]F-FDG PET/CT

Abstract

Purpose: To compare the efficacy of [⁶⁸Ga]Ga-FAPI-04 PET/CT in primary or recurrent tumors and metastatic lesions of epithelial ovarian cancer (EOC) with that of fluorine-18 fluorodeoxyglucose ([¹⁸F]F-FDG) PET/CT.

Methods: Forty-nine patients (median age, 57 years; IQR, 51-66 years) with histologically proven primary or relapsed EOC were enrolled. Participants underwent [¹⁸F]F-FDG and [⁶⁸Ga]Ga-FAPI-04 PET/CT. The detection rate, diagnostic accuracy, semiquantitative parameters, tumor staging, and clinical management of the tracers were compared. The diagnostic performance of [¹⁸F]F-FDG and [⁶⁸Ga]Ga-FAPI-04 PET/CT was evaluated and compared using surgical pathology. Differences between methods regarding the peritoneal cancer index (PCI) using preoperative imaging, surgical PCI, and tumor markers (CA125, HE4) were also assessed regarding peritoneal metastases.

Results: Among the 49 patients, 28 had primary EOC; 21 had relapsed EOC. [⁶⁸Ga]Ga-FAPI-04 PET/CT outperformed [¹⁸F]F-FDG PET/CT in detecting peritoneal metastases (96.8% vs. 83.0%; p < 0.001), retroperitoneal (99.5% vs. 91.4%; p < 0.001), and supradiaphragmatic lymph node metastases (100% vs. 80.4%; p < 0.001). Compared with [¹⁸F]F-FDG, [⁶⁸Ga]Ga-FAPI-04 showed higher SUVmax for peritoneal metastases (17.31 vs. 13.68; p = 0.026) and retroperitoneal (8.72 vs. 6.56; p < 0.001) and supradiaphragmatic lymph node metastases (6.39 vs. 4.20; p < 0.001). Moreover, [⁶⁸Ga]Ga-FAPI-04 PET/CT showed higher sensitivity compared with [¹⁸F]F-FDG PET/CT for detecting metastatic lymph nodes (80.6% vs. 61.3%; p = 0.031) and peritoneal metastases (97.5% vs. 75.9%; p < 0.001), using surgical pathology as the gold standard. Compared with [¹⁸F]F-FDG PET/CT, [⁶⁸Ga]Ga-FAPI-04 PET/CT led to an upgrade in 14.3% and 33.3% of treatment-naive and relapse participants, resulting in management changes in 10.7% and 19.0% of the patients, respectively. The median PCI_FAPI scores were significantly higher than PCI_FDG (15 vs. 11; p < 0.001) and positively correlated with CA125 and HE4 levels and surgical PCI.

Conclusion: [⁶⁸Ga]Ga-FAPI-04 PET/CT achieved higher sensitivity than [¹⁸F]F-FDG PET/CT in the detection and diagnosis of lymph node and peritoneal metastases, suggesting advantages regarding the preoperative staging of patients with EOC and, thereby, improving treatment decision-making.

Trial registration: NCT05034146. Registered February 23, 2021.

Keywords: Ovarian cancer; PET/CT; [18F]F-FDG; [68Ga]Ga-FAPI-04.