This is an observational, single center, imaging study. The CD patients with active disease will be assessed by \[68Ga\]Ga-DOTA-Siglec-9 and \[15O\]H2O PET/MRE. Patients with high clinical suspicion of small intestine's CD in outpatient gastroenterology clinic of Turku University Hospital will be recruited. The patients must fulfil the eligibility criteria and give their signed approvement prior to their enrolment into the study. 20 patients with high suspicion of active small bowels CD will be enrolled to being evaluated for potential participation in this study. In patients with diagnosed small bowels CD, PET-MRE will be repeated 3 months after the initial imaging (and based on clinical diagnostic started medication) to verify disease remission/inadequacy of the treatment. Assessments for CD clinical disease activity will be performed at screening and \[68Ga\]Ga-DOTA-Siglec-9 and \[15O\]H2O PET/MRE assessments will be performed within a month for each patient. After PET/MRE all patients can be treated according to patients' needs with immunosuppressive drugs. Follow-up visits are organized at after PET/MRE imaging at gastroenterology outpatient clinic.