Comparison of 68Ga-FAPI-04 and fluorine-18-fluorodeoxyglucose PET/computed tomography in the detection of ovarian malignancies

Background: Currently, fluorine-18-fluorodeoxyglucose (18F-FDG) is the most frequently used diagnostical radiotracer for PET/computed tomography (PET/CT) in ovarian malignancies. However, 18F-FDG has some limitations. The fibroblast activation protein inhibitor (FAPI) previously demonstrated highly promising results in studies on various tumor entities and 68Ga-labeled FAPI presents a promising alternative to 18F-FDG. This study aimed to compare the performance of 68Ga-FAPI and 18F-FDG PET/CT for imaging of ovarian malignancies.

Methods: A total of 27 patients were included in this retrospective study conducted at the Affiliated Hospital of Southwest Medical University between June 2020 and February 2022. The 18F-FDG and 68Ga-FAPI uptakes of tumors, lymph nodes, and distant metastases were quantified using the maximum standardized uptake values, and the tumor-to-background ratios were also evaluated and calculated by using the Wilcoxon signed-rank test.

Results: Twenty-one patients with suspected (n = 11) and previously treated ovarian malignancies (n = 10) were in statistical analysis finally. For detecting tumors, 68Ga-FAPI PET/CT was more sensitive than 18F-FDG PET/CT [14 of 14 (100%) vs. 11 of 14 (78%)], lymph node metastases [75 of 75 (100%) vs. 60 of 75 (80%)] and superior to 18F-FDG PET/CT in terms of the peritoneal and pleural metastases [9 of 9 (100%) vs. 5 of 9 (56%)]. For four of the newly diagnosed patients (n = 11), 68Ga-FAPI PET/CT upstaged the clinical stage compared to 18F-FDG PET/CT.

Conclusion: 68Ga-FAPI PET/CT has superior potential in the detection of ovarian cancers, especially in peritoneal carcinomatosis. 68Ga-FAPI PET/CT may be a promising supplement for staging and follow-up of ovarian malignancies.