Pulmonary Perfusion Scan
A pulmonary perfusion scan looks at the blood flow to the lung tissue. It is used most often to diagnose a blood clot in the lung, known as a pulmonary embolus.
Who is a candidate for the test?
The healthcare professional may order a pulmonary perfusion scan in the following circumstances:
the person has chest pain or shortness of breath
results of the person's pulmonary function tests are abnormal
a woman is on oral contraceptives and shows signs of a pulmonary embolus, or a blood clot in the lung
in a person with leg pain, to evaluate whether a clot from a leg vein may have broken off and traveled to the lung
an individual has breathing problems after surgery
How is the test performed?
For the scan, a person is often asked to sit upright. If a person is unable to sit, he or she can lie flat on a table. A radioactive substance known as Tc-99m macroaggregated albumin will be injected into a vein in the arm. The substance gives off gamma rays from within the body. These rays are detected by a "gamma camera" that is positioned over the chest.
A computer then generates pictures that can be interpreted by a radiologist. The lungs will be scanned in multiple positions (usually six). The exam takes approximately 45 minutes. Usually, a second test called a pulmonary ventilation scan
will follow the perfusion scan.
What is involved in preparation for the test?
The individual will undress from the waist up and put on an exam gown. All jewelry and metal objects will be removed.
What do the test results mean?
A normal perfusion scan indicates that all sections of both lungs are receiving adequate blood flow. If a section of lung is not receiving blood flow, but is receiving airflow as determined by the ventilation scan, it is likely that the person has a pulmonary embolus.