This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
[{'content': 'In aoic dissection most accurate investigation is : \nSelect and explain. \nA. ECG, B. CT scan, C. Aoography, D. MRI scan', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. MRI scan', 'role': 'assistant'}]