Inclusion Criteria:  (i) adult patients (aged 18 years or order); (ii) patients with suspected or newly diagnosed or previously treated malignant tumors (supporting evidence may include magnetic resonance imaging (MRI), CT, tumor markers and pathology report); (iii) patients who had scheduled both 8Ga-DOTA-FAPI-46 and 68Ga-DOTA-2P(FAPI)2 PET/CT PET/CT scans; (iv) patients who were able to provide informed consent (signed by participant, parent or legal representative) and assent according to the guidelines of the Clinical Research Ethics Committee.  Exclusion Criteria:  (i) patients with non-malignant lesions; (ii) patients with pregnancy; (iii)the inability or unwillingness of the research participant, parent or legal representative to provide written informed consent.