Crohn's disease (CD) is a chronic transmural inflammatory bowel disease. Prolonged episodes of inflammation can lead to intestinal fibrosis, leading to intestinal stenosis and obstruction. Inflammatory stenosis can be alleviated through anti-inflammatory treatment, while fibrotic stenosis requires endoscopic dilation or surgical treatment. Early detection of the presence and severity of intestinal fibrosis in CD is the key to treatment strategies. Currently, there are certain limitations in the non-invasive evaluation methods for intestinal fibrosis, and it is urgent to develop a new imaging method to achieve non-invasive diagnosis of the degree of fibrosis. Fibroblast activation protein (FAP) is a marker of intestinal fibrosis in CD. Based on the principle that fibroblast activation protein inhibitor (FAPI) can specifically bind to FAP, FAPI radioactive tracers can achieve targeted tracing and quantification of FAP in vivo. Therefore, 18F-FAPI positron emission tomography (PET) imaging technology has a good application prospect in the noninvasive diagnosis and evaluation of CD intestinal fibrosis. Based on the successful testing of 18F-FAPI PET imaging in the early stage of the project team to evaluate the nature of CD intestinal stenosis, this project intends to take patients with CD intestinal stenosis as the research object, and use postoperative histopathological analysis as a reference index to evaluate the role of 18F-FAPI combined with 18F-2-fluoro-2-deoxy-D-glucose fluorodeoxyglucose(18F-FDG) PET imaging in the qualitative diagnosis of CD intestinal wall fibrosis, as well as the differential diagnosis ability of inflammatory and fibrous stenosis in CD patients, and establish a diagnostic model and evaluation system. Achieving a noninvasive, stable, and objective diagnosis and evaluation of the degree of intestinal fibrosis in CD patients at the molecular level will provide imaging evidence for treatment decision-making, progress, and prognosis of CD patients, and also play an important support role in the development of anti fibrosis drugs, selection of suitable patients, and efficacy evaluation.