<prompt> Gold standard for diagnosing pulmonary embolism:X-ray chestVentilation perfusion scanBlood gas analysisDoppler  <response>: B i.e. V-P Scan Investigation of choice IOC for diagnosing pulmonary embolism is pulmonary aeriography followed by ventilation - perfusion scanQ. Advantages Disadvantages of various tests for DTE Dx Test Advantages Disadvantages 1. Plasm D-dimer ELISA Normal results make PE highly unlikely Level is elevated in various systemic illnesses 2. Lung V-P Scanning Standard initial imaging test for PEQ. High probability scans are reliable for detecting PE . normalnear normal scans are reliable for precluding PE Most scans are neither high probability nor normalnear normal; most are equivocal 3. Pulmonary angiography Gold standard for diagnosisQ Invasive, Costly Uncomfoable ; so not a first line investigation 