Fundamentals of PET and PET/CT Imaging

Abstract

Positron emission tomography (PET) has been in existence since the 1970s due in large part to the pioneering work of Michael Phelps, PhD, Michel Ter-Pogossian, PhD, and others in the fields of medical physics and nuclear medicine [1]. Although initially a research tool, over the past 10 years PET has become increasingly used in the clinical setting, particularly after CMS (the Centers for Medicare and Medicaid Services, formerly known as the Health Care Financing Administration or HCFA) began reimbursing for PET evaluation of myocardial perfusion in 1995. Clinical utilization rose dramatically in 1998, when CMS began reimbursing for PET evaluation of solitary pulmonary nodules and initial staging of lung cancer. (CMS coverage as it relates to PET is covered in detail in Chapter 2.) 1998 also saw the creation of the first PET/computed tomography (CT) hybrid system, and in 2001, such systems became commercially available. Major manufacturers such as General Electric, Siemens, and Philips are now combining their latest CT technology with their latest PET technology to create very powerful hybrid systems that are the industry mainstay. PET/CT hybrids represent the state of the art in PET scanning, and it is estimated that PET/CT combination systems comprise 90% of sales in the current PET market [2]. The evolution of PET from its beginnings as an instrument of research to its present day wide and growing use in cancer, cardiac, and neurological imaging has resulted in instrumentation that is making a major impact in clinical care. Before launching an in-depth discussion of the clinical applications of PET, it is important to describe the fundamental basic scientific principles behind nuclear medicine imaging, of which PET is a part.