Nuclear perfusion imaging, or a nuclear stress test, is a diagnostic procedure assessing heart blood supply under stress and rest conditions. A small amount of radioactive material is injected to evaluate blood flow and heart function, helping determine the risk of a heart attack. This test, using thallium or sestamibi, captures images during exercise and rest, revealing areas with inadequate blood supply. Results, interpreted by a board-certified nuclear cardiologist, guide treatment plans for serious heart conditions.