Abnormal adnexal uptake in 68Ga-FAPI PET/CT: from physiological variants to malignant characterization

BACKGROUND: Ga-FAPI PET/CT for early and precise lesion characterization. METHODS: Ga-FAPI PET/CT. RESULTS: The study included 121 female patients with a mean age of 53.8 ± 12.2 years (18-80 years). A total of 184 adnexal lesions with abnormal uptake were identified. Pathology/follow-up confirmed 82.6% as malignancies, comprising 84 primary and 16 metastatic cases. Additionally, 2 borderline tumors and 19 benign lesions were detected. The positive predictive value was 83.5%. SUVmax differed significantly among primary malignant, metastatic, and benign lesions (12.52 ± 5.41 vs. 9.78 ± 3.39 vs. 5.52 ± 4.17). In the subset of patients with available pathological specimens, SUVmax showed weak to moderate positive correlations with Ki-67 (r = 0.361, p < 0.001) and p53 (r = 0.419, p < 0.001). Notably, the mean SUVmax in the Ki67 > 20% group was significantly higher than in the Ki67 ≤ 20% group (p < 0.001). ROC analysis showed an AUC of 0.85 of SUVmax alone for diagnosing malignant adnexal lesions, increasing to 0.89 when combined with tumor markers. DISCUSSION: Ga-FAPI PET/CT demonstrates high diagnostic performance for ovarian lesions. Among pathologically confirmed cases, SUVmax correlates with proliferative activity and malignant potential, supporting its role in diagnostic optimization.