18 F-FAPI-04 PET/CT in the Evaluation of Patients With Cervical Cancers : Head-to-Head Comparison With 18 F-FDG PET/CT.

Abstract

Background: To explore the potential utility of 18 F-AlF-NOTA-fibroblast activation protein inhibitor (FAPI)-04 PET/CT (denoted as 18 F-FAPI-04 PET/CT) in the evaluation of cervical cancer through a head-to-head comparison with 18 F-FDG PET/CT for detecting primary tumors and metastatic lymph nodes.

Patients and methods: A total of 22 patients with a pathologic diagnosis of cervical cancer underwent 18 F-FDG PET/CT and 18 F-FAPI-04 PET/CT within a 7-day period. Out of the 22 patients, 19 (median age, 62.3 y) were included in the final analysis. Comparisons were made between the ability of 18 F-FDG PET/CT and 18 F-FAPI-04 PET/CT to detect primary lesions and metastatic lymph nodes; semiquantitative PET/CT parameters were also analyzed, including SUV max , SUV mean , metabolic tumor volume (MTV for 18 F-FDG) and fibroblast tumor volume (FTV for 18 F-FAPI-04), tumor lesion glycolysis (TLG for 18 F-FDG) and tumor lesion FAPI (TLF for 18 F-FAPI-04), and tumor-to-background ratios (TBR liver and TBR blood ), calculated by dividing the SUV max of the lesion by the SUV mean of normal liver or blood pool.

Results: 18 F-FAPI-04 PET/CT identified a greater number of primary lesions and metastatic lymph nodes compared with 18 F-FDG PET/CT. 18 F-FAPI-04 PET/CT detected 19/19 primary tumors, achieving a detection rate of 100%, while 18 F-FDG PET/CT identified 18/19 primary tumors, with a detection rate of 95%. The PPV for both tracers was 100%, the NPV for 18 F-FDG PET/CT was 0%. For metastatic lymph nodes, 18 F-FAPI-04 PET/CT detected 82 nodes in 7 patients, while 18 F-FDG PET/CT detected 44 nodes in the same 7 patients. TBR was significantly higher for 18 F-FAPI-04 PET/CT compared with 18 F-FDGPET/CT for primary lesions (TBR blood : 16.33 vs 9.83, P = 0.005; TBR liver : 21.59 vs 7.04, P < 0.0001) and metastatic lymph nodes (TBR blood : 9.16 vs 7.64, P = 0.033; TBR liver : 10.38 vs 5.29, P < 0.0001). No significant differences were observed in other semiquantitative parameters.

Conclusions: 18 F-FAPI-04 PET/CT had superior performance in detecting primary lesions and metastatic lymph nodes in cervical cancer compared with 18 F-FDG PET/CT. 18 F-FAPI-04 exhibited lower uptake in normal tissues, leading to a higher TBR. These findings imply that 18 F-FAPI-04 PET/CT has potential for clinical application in cervical cancer.