This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pancreas, Subject name: Surgery
[{'content': 'Imaging IOC for acute pancreatitis \nSelect and explain. \nA. CT scan, B. USG, C. X ray, D. MRI', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) CT ScanRef: Sabiston Page 1530/ 20th edition* The imaging investigation of choice for acute pancreatitis is CECT scan.* CECT scan is done after 72 hours of onset- ideally on the 7th day.', 'role': 'assistant'}]