To evaluate the potential usefulness of 18F-FAPI-04 positron emission tomography/computed tomography (PET/CT) and positron emission tomography/magnetic resonance imaging （PET/MR）for the diagnosis of primary and metastatic lesions, detection of recurrence or assessment of pathologic response in various types of cancer.

Subjects with various types of cancer underwent 18F-FAPI-04 PET/CT and PET/MR imaging either for an initial assessment, recurrence detection or assessment of pathologic response. Tumor uptake was quantified by the maximum standard uptake value (SUVmax) and tumor to background (TBR). Using histopathology and follow-up as gold standard, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of 18F-FAPI-04 PET/CT and PET/MR were calculated.

Inclusion Criteria:

patients with suspected or new diagnosed or previously treated malignant tumors (supporting evidence may include MRI, CT, tumor markers and pathology report); 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:

patients with non-malignant lesions; patients with pregnancy; the inability or unwillingness of the research participant, parent or legal representative to provide written informed consent.

patients with suspected or new diagnosed or previously treated malignant tumors.