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': 'A 55 year old man who has been on bed rest for the past 10 days, complain of breathlessness and chest pain. The chest X-ray is normal. The next step in the investigation should be – \nSelect and explain. \nA. Lung ventilation – perfusion scan, B. Pulmonary arteriography, C. Pulmonary venous wedge angiography, D. Echocardiography', 'role': 'user'}, {'content': 'Answer: A \nExplanation: This patient has a high clinical likelihood of pulmonary embolism because clinical assessment score is more than 4:-\n\n\nSigns & symptoms of PE (Breathlessness & chest pain) → score 3.0\nImmobilization (bed rest) > 3 days → score 1.5\n\n\nSo, the total score is 4.5. Therefore, imaging test should be done. CT contrast is the imaging test of choice.', 'role': 'assistant'}]