This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular Radiology, Subject name: Radiology
[{'content': 'IOC for Acute Aoic Dissection \nSelect and explain. \nA. Usg, B. CT-angio, C. Mr-Angio, D. Doppler', 'role': 'user'}, {'content': 'Answer: B \nExplanation: IOC for acute Aoic Dissection is CT-Angio In Unstable patients- Transesophageal Echocardiography MRI is NOT used in Acute conditions but is helpful in chronic dissections to better delineate the true and false lumen - Dissection of aerial wall forming shreds within false lumen - COB WEB SIGN - False lumen form an acute angle giving BEAK SIGN in aoic dissection COB WEB SIGN BEAK SIGN', 'role': 'assistant'}]