Diagnosing: When diagnosing a pulmonary embolism, there are a few ways to do so. One way to diagnose a PE is a D-dimer test; this test measures the amount of D-dimer in the blood, or protein that is released when blood clots break down. In this case, Linda's D-dimer test will most likely come back high. Another way to diagnose a PE is a helical CT angiogram, which is an X-ray technique where dye is put into the vascular system and the patient is spun around multiple times, giving a 3D image of the vasculature. Here we might be able to see blockage via this method. One other method that is common is the ventilation perfusion (VQ) scan. This is a medical imaging test that assesses how well air and blood flow through the lungs. This procedure is performed by having the patient inhale radioactive gas to assess the ventilation, and a radioactive tracer is injected into the bloodstream to evaluate the patient's perfusion. If gas or tracer are not evenly distributed, there is a key sign of a potential PE