This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Imaging of Interstitial Lung Disease, Subject name: Radiology
[{'content': 'Gold standard test for pulmonary embolism: (Repeat) \nSelect and explain. \nA. CT Angiography, B. MRI, C. PET, D. Echocardiography', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans: A (CT Angiography) Ref: Harrison's Principles of Internal Medicine, 18ed. Chapter 262. Deep Venous Thrombosis and Pulmonary ThromboembolismExplanation:Tests:D-Dimer assay- sensitive 'rule out' test False positive inMI, pneumonia, sepsis, cancer, pregnancy, post-op stateABG- low- p02 & pC02. high A-a gradientS.troponin, heart- type fatty acid binding protein. BNP, NT-pro BNP) due to RV microinfarctionECG:Sinus tachycardiaAcute right axis deviationRBBBS1Q3TS signT-wave inversion in V1-V4CXR:Hampton's sign-peripheral wedge shaped density above diaphragmWestermark's sign - focal oligemiaPalla's sign- enlarged right pulmonary arteryECHO- Mc-Connel's sign- Hypokinesia of RV free wall, normal RV apexMultidetector-row spiral CT- Very sensitive, non invasive testPulmonary angiography with CT -- Gold standard Test (Most specific)", 'role': 'assistant'}]