This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pulmonary Embolism, Subject name: Medicine
A person is diagnoses with pulmonary embolism invasive modality for diagnosis is - 
Select and explain. 
A. Venous ultrasonography, B. Pulmonary angiography, C. CT, D. MRI
B: Pulmonary angiography
Answer: B: Pulmonary angiography 
Explanation: Ans. is 'b' i.e., Pulmonary angiography o The definitive diagnostic for pulmonary thromboembolism is pulmonary angiography.o It is the most specific investigation for pulmonary> thromboembolism but it is expensive time consuming and invasive,o Therefore chest CT with contrast has virtually replaced angiography as the diagnostic test.o Best investigation when there is clinical suspicion of pulmonary embolism - Contrast enhanced CT.