What type of examination visualizes pulmonary blood flow after injecting a radioactive contrast medium?

The examination that visualizes pulmonary blood flow after injecting a radioactive contrast medium is known as a lung ventilation scan, specifically a ventilation-perfusion (V/Q) scan. This type of scan assesses the circulation of air and blood within the lungs, helping to identify issues such as pulmonary embolism or other vascular abnormalities.

In a V/Q scan, a radioactive tracer is injected into the bloodstream, allowing for imaging of blood flow (perfusion) through the pulmonary vessels. By comparing this with a ventilation scan, where another radioactive substance is inhaled to assess airflow in the lungs, healthcare providers can evaluate both ventilation and perfusion. This helps in diagnosing conditions that affect the lung's ability to oxygenate the blood effectively.

The other examination types provided do not serve this specific purpose. A CT scan could provide detailed images of the lungs and blood vessels but does not specifically visualize blood flow via a radioactive medium. Magnetic resonance imaging (MRI) offers a different imaging modality and is not typically used for examining lung function or blood flow in this context. Pulmonary function tests measure how well the lungs are working by assessing airflow and lung volumes, but they do not involve visualizing blood flow using radioactive contrast. Thus, the lung ventilation scan is the most appropriate choice for