Which test for PE involves both breathing and injection of an isotope?

The correct answer is a V/Q scan, which stands for ventilation-perfusion scan. This test is specifically designed for evaluating pulmonary embolism (PE) and integrates both breathing (ventilation) and injection of an isotope (perfusion) components to assess blood flow as well as airflow in the lungs.

During the ventilation portion of the test, the patient inhales a radioactive gas or aerosol, which allows for imaging of airflow in the lungs. The perfusion segment involves the intravenous injection of a radioactive isotope that travels through the bloodstream to visualize blood flow in the pulmonary vasculature. By comparing the patterns of ventilation and perfusion, the V/Q scan can identify areas of the lung that are receiving air but not blood, indicative of a potential blockage, such as a pulmonary embolism.

This combination of imaging airflow and blood flow makes the V/Q scan uniquely suited for diagnosing PE, as it provides critical information about how well the lungs are ventilated in relation to blood perfusion. In contrast, other imaging modalities, such as pulmonary angiography, CT scans, and MRIs, do not utilize this dual approach specifically for PE assessment.