Lung Scan

   1. Purpose of Test

To assess the ability of the lungs to ventilate (take in air) and the ability of the lungs' tiny arteries (arterioles) to receive blood. To detect a blood clot in an artery leading to the lung (pulmonary embolism). To assess the function of the lungs in anticipation of lung surgery.

A gamma scintillation camera picks up radiation emitted by the radionuclide particles in your lung tissue or in the arterioles and produces an image showing which portions are receiving air and blood, which is displayed on the screen or printed out on film.

   2. What to expect during procedure

For the ventilation part of the test, you are seated and a mask is placed over your nose and mouth.

You follow specific instructions about inhaling and exhaling, and you breathe in a combination of air and radioactive gas. A large scanning camera takes pictures of your chest. For the perfusion part of the test, radioactive material is injected intravenously through your hand or arm. You sit or lie down and breathe freely as the scanning camera takes pictures of your chest at various angles.

Sometimes, SPECT (single photon emission computed tomography) technology may be used to produce a three-dimensional lung scan.

   3. How to prepare for test

A regular chest X-ray is usually performed within 12 hours before this test or immediately afterward to identify any abnormalities that would alter the scan. Before the scan, you remove clothing and jewelry above the waist.