What is the difference between a Lexistress test and a MUGA scan? 

This is a very broad question, but basically these are two totally different tests used in nuclear cardiology to look at aspects of the heart and its function.

The “Lexistress” test (also known as a form of myocardial perfusion imaging [MPI]) gives information about the blood flow to the heart muscle. It involves the injection of a drug Lexiscan® (brand name for regadenoson) followed by the injection of a radioactive drug that allows the department to take pictures of the heart. IF the patient is able, this sort of test can also be done using exercise (commonly on a treadmill) instead of or in addition to the Lexiscan®.

The MUGA (short for Multiple Gate Acquisition) scan is a test that uses a different radioactive material, that is bound to the patient’s red blood cells, to take pictures of the blood that is being pumped by the heart. The test can be done at rest alone and/or with exercise (usually on a bicycle) to measure how well the heart as a whole and its various parts are contracting.

One way of looking at these tests is to think of a doughnut. The Lexistress test is used to make pictures (“images”) of the wall of the heart (like the pastry part of the doughnut) while the MUGA test makes pictures of the part of the heart filled with blood (like the hole in the doughnut). So, while both tests take pictures of the heart, they are looking at different parts of the heart and so give the physician different information. Some patients, depending on their particular medical problem, need one test while other patients need the other test. Occasionally, a patient may need both tests, again because they provide different information about the heart’s function.