A multigated acquisition scan, or MUGA scan, is also sometimes called an equilibrium radionuclide ventriculogram. This is a diagnostic imaging test that evaluates the health of a heart and whether it is pumping blood properly. Patients can expect to have two injections prior to the MUGA scan, as well as electrodes placed on their chests. A special imaging tool called a gamma camera is then used to take images of the heart. This test is not painful; however, some patients may experience mild discomfort from the injections.
The doctor may recommend a MUGA scan for a variety of reasons. It is a means of assessing damage in patients who have suffered a heart attack, as well as a tool for evaluating the health of cancer patients who will undergo chemotherapy. Before undergoing a MUGA scan, patients must inform the doctor about all of their medical conditions, because these may affect the test. These can include an irregular heartbeat and whether they have recently had other imaging tests performed. Being obese and taking certain medications for a heart condition, as well as pregnancy, may prevent a patient from undergoing this scan.
In most cases, the patient will not need to restrict medication or food prior to a MUGA scan. Some patients may be asked to avoid food, liquids, and caffeine, as well as tobacco for about four to six hours before their appointment. Patients should plan to wear comfortable clothing and they may be asked to wear a hospital gown. They will be able to drive themselves home afterward, as well as resume all other normal activities immediately.
The MUGA scan may take between one to three hours. Upon arriving at the facility, the patient will be directed to a nuclear medicine technologist, who will administer the first injection of stannous chloride into a vein. After waiting for 30 minutes, he will then inject Technetium 99, which is a radioactive substance, into the bloodstream. This injection “tags” red blood cells, allowing them to be viewed by the imaging device. The radioactive substance is not harmful and does not result in adverse effects, because it is given in a small dose.
Three electrodes are then positioned on the patient's chest so the technologist may monitor the heart's activity during the MUGA scan. The patient must then lie very still on an exam table underneath the gamma camera, which picks up signals from the radioactive tracer. It measures how much blood the heart pumps, a measurement called the ejection fraction. In a normal heart, this will be in a range of 50 to 70 percent. Following the MUGA scan, the doctor will assess the results and discuss them with the patient.