Positron Emission Tomography (PET) Study of Changes in [11C]AZ14132516 Uptake Following Administration of AZD7798 to Healthy Participants and Patients With Crohn's Disease

The purpose of this study is to measure the changes in small bowel uptake of radioligand \[11\^C\]AZ14132516 after intravenous (IV) administration of single and repeat doses of AZD7798 in healthy participants and participants with Crohn's disease. Study details include: * The study duration will be variable (adaptive design). * For Panels 1-5, there will be 5 in-person study visits: 1 screening visit, 1 visit for the baseline PET examination, 1 residential (24 hour) visit for AZD7798 administration and 2 visits for repeated PET examinations. There will be a final follow-up virtual visit (telephone call). * For Panel 6, there will be 7 in-person study visits: 1 screening visit, 1 visit for the baseline PET examination, 2 residential (24 hour) visits for AZD7798 administration, 1 visit for pharmacokinetic (PK) blood sample and 2 visits for repeated PET examinations. There will be a final follow-up virtual visit.