How to prepare for a ventilation perfusion scan?
A V/Q scan takes approximately 20 to 30 minutes and consists of two parts. During the ventilation part, the patient will have a face mask placed over his or her mouth and nose and will be asked to inhale oxygen and a radioactive gas that has no smell. The mask will be left on for approximately 5 to 10 minutes, and posterior projection scintigraphic images of the lungs will be obtained. Then the patient will be asked to lie supine in order to receive an intravenous injection of technetium-99m ( 99m Tc) radiolabeled macroaggregated albumin (MAA) to assess the blood flow to the lungs. Scintigraphic images of the lungs are then acquired in multiple projections over a period of approximately 20 minutes. There is no specific preparation for the patient, and the patient does not need to fast in preparation for the study. Although patients can receive oxygen, patients who are dependent on significant amounts of oxygen (i.e., require O 2 by face mask) are unlikely to be able to successfully perform the ventilation portion of the study, although the perfusion scan would not be affected.