Positron Emission Tomography (PET) scans show the chemical functioning of organs and tissues while other imaging techniques [such as X-ray, MRI and CT scans] show structure. This difference is what makes PET technology particularly useful for the detection of coronary artery disease (blockages of blood vessels to the heart). PET permits evaluation of myocardial perfusion (blood flow to the heart) and metabolism with superior accuracy. The results help your physician identify the extent of heart disease and decide if treatment for blockages of blood vessels is needed. The most common use of PET imaging in cardiology is to identify heart muscle weakened, but not irreversibly damaged, by blocked vessels.