[68Ga]Ga-FAPI PET/CT Improves the T Staging of Patients with Newly Diagnosed Nasopharyngeal Carcinoma: A Comparison with [18F]F-FDG

Purpose This study aimed to explore the value of [ 68 Ga]Ga-labelled fibroblast activation protein inhibitor ([ 68 Ga]Ga-FAPI) positron emission tomography/computed tomography (PET/CT) in the initial staging of patients with newly diagnosed nasopharyngeal carcinoma (NPC), compared with 2-deoxy-2[ 18 F]fluoro-D-glucose ([ 18 F]F-FDG) PET/CT. Materials and Methods Forty-seven treatment-naïve patients with newly diagnosed NPC underwent magnetic resonance imaging (MRI), [ 68 Ga]Ga-DOTA-FAPI-04 PET/CT and [ 18 F]F-FDG PET/CT within 1 week. The diagnostic efficiency of all imaging modalities for evaluating primary tumour extension was compared from the two aspects of soft tissue and bony structure involvement. The accuracy of two PET/CT methods for diagnosing cervical lymph node (CLN) metastases was compared, and MRI served as the standard reference. T and N stages were assessed by MRI, [ 68 Ga]Ga-FAPI PET/CT and [ 18 F]F-FDG PET/CT. Immunohistochemical (IHC) staining for FAP was conducted in 22 of the patients. Results [ 68 Ga]Ga-FAPI PET/CT outperformed [ 18 F]F-FDG PET/CT in the assessment of primary tumour invasion in the cavernous sinus (10 vs. 1, p