This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System, Subject name: Radiology
"Gold standard" study for diagnosis of pulmonary embolic episode is: 
Select and explain. 
A. Ventilation perfusion scan, B. Pulmonary angiography, C. Chest x-ray, D. Multi slice CT
B: Pulmonary angiography
Answer: B: Pulmonary angiography 
Explanation: Ans. B. Pulmonary angiographyAlthough pulmonary angiography is supposed to be the definitive and gold standard means of diagnosing PULMONARY EMBOLISM with the decreasing availability of pulmonary arteriography and increasing use of other non-invasive tests like spiral CT, the exact role of pulmonary arteriography is now less clear and there are only few indications for it, especially in absence of spiral CT or MRI.