According to Cancer(dot)net, A multigated acquisition (MUGA) scan creates video images of the ventricles (lower chambers of the heart that hold blood) to check whether they are pumping blood properly. It shows any abnormalities in the size of the ventricles and in the movement of the blood through the heart. Other names for this test include cardiac blood pooling imaging, nuclear heart scan, nuclear ventriculography, and radionuclide ventriculography.
Some people with cancer who receive chemotherapy or other drugs may need this test before cancer treatment to identify preexisting heart conditions or during or after cancer treatment to identify chemotherapy-related heart damage. Survivors of childhood cancer who have had radiation therapy to the chest, spine, or upper abdomen; bone marrow/stem cell transplantation; or certain types of chemotherapy may need a MUGA scan as part of their follow-up
care to identify heart-related late effects (side effects that occur more than five years after treatment).
I hope this helps.