Nuclear myoperfusion imaging (MPI) is a procedure that allows your physician to assess the blood flow to the heart muscle. Nuclear refers to the tracer that is injected into the vein and contains a small amount of radiation similar to that used in other radiology procedures such as Xrays. 

The information from the test will address isssues such as the pump function of your heart and if you have any blockage in the heart arteries (coronaries).

The test is performed in two parts: taking images of the heart at rest and during stress. For best quality, these two parts should be done on separate days however the order of the tests is not important.

On day one the heart is stressed either by exercise or by using a medication that can expand the arteries thereby creating an effect as if you were exercising. Once the arteries are expanded, a small amount of a radioactive imaging agent will be injected. Later on, images of the heart will be taken with a special camera which will show if any part of your heart is not getting enough blood.

On day two, images of your heart will be taken during normal function at rest. By comparing the pictures from both days, physicians will be able to determine if there is any severe blockage in your heart arteries.