For example, FAP-targeted PET/CT or PET/MRI has shown diagnostic value in multiple cancers, such as lung cancer, breast cancer, HNSCC and gastric cancer (Backhaus et al., 2022; Kumar et al., 2022; Promteangtrong et al., 2022; Wang et al., 2022). The gene discussed is FAP; the disease is head and neck squamous cell carcinoma.