There are two types of lung scans. A lung perfusion scan is a nuclear medicine test that provides your doctor with a picture of blood flow to the lungs. A lung ventilation scan tells you doctor how capable your lungs are of taking in air and uses radiopharmaceuticals to produce a picture of how air is distributed in the lungs.
In most cases, lung perfusion scans and lung ventilation scans are done at the same time. These tests are performed to detect pulmonary embolisms, determine how much blood is flowing to lungs, determine which areas of the lungs are capable of ventilation, and to determine how well the lungs are functioning after surgery.
In a lung perfusion scan, a small amount of the protein labeled with a radioisotope is injected into your hand or arm vein. You will be positioned under a special camera that can detect radioactive material, and a series of photographs will be made of your chest. When these images are projected onto the screen called the oscilloscope, they will show how the radioactive protein has been distributed by the blood vessels running through the lungs.
In a lung ventilation scan, a mask will be placed over your nose and mouth, and you will be asked to inhale and exhale a combination of air and radioactive gas. Pictures are then taken that show the distribution of the gas in your lungs. Each test takes 15-30 minutes.