infarction formation of an infarct, which is an area of tissue death due to local lack of oxygen mediastinal pertaining to a mediastinum, which is the space in the chest cavity behind the breastbone and between the two pleural sacs containing the lungs. metastases cancer that started from cancer cells from another part of the body. myocardial refers to the heart's muscle mass myocardium the middle layer of the heart wall nodule a small lump, swelling or collection of tissue PET a highly specialized imaging technique. The acronym stands for Positron Emission Tomography, which literally means to send forth an internal body image with the use of positively charged particles perfusion passage of fluid through vessels of a specific organ resection excision of a portion or all of an organ or other structure revascularization a surgical procedure for the provision of a new, additional or augmented blood supply to a body part or organ stenosis narrowing or stricture of a duct or canal tracers PET tracers are unique and safe radiopharmaceuticals labeled with isotopes such as carbon, oxygen, nitrogen and fluorine - all basic elements of biological substrates.