The performance of 68Ga-FAPI-04 PET/CT in head and neck squamous cell carcinoma: a prospective comparison with 18F-FDG PET/CT

Purpose This study was designed to compare the performance of Ga-68-FAPI-04 and F-18-FDG PET/CT for initial staging and recurrence detection of head and neck squamous cell carcinoma (HNSCC). Methods Prospectively, 77 patients with histologically proven or highly suspected HNSCC underwent paired F-18-FDG and Ga-68-FAPI-04 PET/CT in a week for either initial staging (n = 67) or restaging (n = 10). The diagnostic performance was compared for the two imaging approaches, especially for N staging. SUVmax, SUVmean, and target-to-background ratio (TBR) were assessed for paired positive lesions. Furthermore, change in management by Ga-68-FAPI-04 PET/CT and histopathologic FAP expression of some lesions were explored. Results F-18-FDG and Ga-68-FAPI-04 PET/CT exhibited a comparable detection efficiency for primary tumor (100%) and recurrence (62.5%). In the twenty-nine patients receiving neck dissection, Ga-68-FAPI-04 PET/CT showed greater specificity and accuracy in evaluating preoperative N staging than F-18-FDG based on patient (p = 0.031 and p = 0.070), neck side (p = 0.002 and p = 0.006), and neck level (p < 0.001 and p < 0.001). As for distant metastasis, Ga-68-FAPI-04 PET/CT detected more positive lesions than F-18-FDG (25 vs 23) and with higher SUVmax (7.99 +/- 9.04 vs 3.62 +/- 2.68, p = 0.002) by lesion-based analysis. The type of neck dissection in 9 cases (9/33) was altered by Ga-68-FAPI-04. Overall, clinical management was significantly changed in 10 patients (10/61). Three patients had a follow-up Ga-68-FAPI-04 PET/CT post neoadjuvant therapy: One showed complete remission, and the others showed progression. The Ga-68-FAPI-04 uptake intensity was confirmed to be consistent with FAP expression. Conclusion Ga-68-FAPI-04 outperforms F-18-FDG PET/CT in evaluating preoperative N staging in patients with HNSCC. Furthermore, Ga-68-FAPI-04 PET/CT also shows the potential in clinical management and monitoring response to treatment.