68Ga-FAPI-04 PET Imaging in Early Response Evaluation of Rectal Cancer Patients Treated With Immunotherapy: A Single-center Clinical Study

This study is a prospective monocentric study aimed to explore the value of 68Ga-FAPI-04 PET imaging in early response evaluation of rectal cancer patients treated with immunotherapy. Patients with histopathologically confirmed diagnosis of rectal cancer will be recruited and undergo 68Ga-FAPI-04 and 18F-FDG PET imaging before treatment and after short-course radiotherapy and two cycles of neoadjuvant chemotherapy plus immunotherapy. The two imaging intervals will be completed two days apart. The efficacy of 68Ga-FAPI-04 in early response evaluation will be compared with the general imaging agent 18F-FDG. The general information, clinical data, mpMRI data, 68Ga-FAPI-04 and 18F-FDG PET imaging results and other imaging data of the patients will be collected. The histopathology of the biopsy or surgical specimen after 2 cycles of therapy and follow-up data will be taken as evaluation references. This study plans to set the sample size as 20 cases