Positron emission tomography (PET) is the leading tool in nuclear cardiology for noninvasive assessment of molecular function. Images are obtained via detection of positrons emitted from the decay of an injected radiotracer. Radiotracers are either short-lived isotopes themselves, such as 82Rb, or isotopes that have been incorporated into biological or drug compounds, such as 18F-fluoro-deoxyglucose or 11C-methyl-losartan, respectively. The amount of tracer injected is low enough such that it does not affect the physiological process being imaged. Most isotopes are produced in a cyclotron and undergo radiochemical synthesis to be incorporated into a tracer molecule, requiring an onsite or local cyclotron due to the short half-lives. There has been a shift toward simpler and more cost-effective onsite alternatives, such as the generator-produced tracer 82Rb. Some of the most common clinical and research-based cardiac PET tracers, their characteristics, applications, and the associated imaging protocols are listed in Table 2.1 (Zober et al. 2006; Thackeray and Bengel 2013; Danad, Raijimakers, and Knaapen 2013).