Pulmonary study to identify pulmonary thromboembolism. This is a quick and non-invasive way of identifying pulmonary thromboembolism in dogs and cats. The radionuclide is injected intravenously. Because of its predilection for the lungs, it accumulated in the pulmonary tissue. However, it will be impossible for the radionuclide to accumulate in the lungs if a clot were to be present in the lungs.