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 a patient with high clinical suspicion of pulmonary thromboembolism, the best investigation would be? \nSelect and explain. \nA. D-dimer, B. CT angiography, C. Catheter angiography, D. Color Doppler', 'role': 'user'}, {'content': 'Answer: B \nExplanation: This question is a tricky one. The best method does not mean the most accurate method.\nBest diagnostic test means the test which has high accuracy and less disadvantages.\nThough invasive pulmonary angiography is the most accurate method for diagnosis of PE, it is an invasive procedure.\nOn the other hand, CT chest with contrast is almost as accurate as invasive pulmonary angiography, for the diagnosis of PE; and it is non-invasive.\nInvestigation of choice for PE \xa0 \xa0 \xa0 \xa0\xa0→\xa0\xa0Chest CT with contrast (especially MDCTA)\n\tInvestigation of 2nd choice \xa0 \xa0 \xa0 \xa0 \xa0 \xa0\xa0→\xa0Lung scan (V/Q scan)\n\tBest investigation for PE \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0→\xa0 Chest CT with contrast (MDCTA)\n\tMost accurate investigation for PE \xa0→\xa0\xa0Invasive pulmonary angiography\n\tGold - standard test for PE \xa0 \xa0 \xa0 \xa0 \xa0 \xa0\xa0→ \xa0\xa0Invasive pulmonary angiography\n\tScreening test for PE \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0→\xa0\xa0D-dimer assay', 'role': 'assistant'}]