This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastrointestinal Radiology, Subject name: Radiology
[{'content': "Fat halo sign is associated with \nSelect and explain. \nA. Ulcerative colitis, B. Crohn's disease, C. Plummer Vinson syndrome, D. Chiladiti syndrome", 'role': 'user'}, {'content': "Answer: B \nExplanation: The 'Fat halo sign' refers to a feature seen on CT examination of the abdomen, and represents infiltration of the submucosa with fat, between the muscularis propria and the mucosa. It is characterized by an inner (mucosa) and outer (muscularis propria and serosa) ring of enhancing bowel wall along with a non-enhancing middle layer (submucosa).", 'role': 'assistant'}]