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KEY POINTS
Cardiac positron emission tomography (PET) perfusion imaging offers excellent diagnostic accuracy and image quality with low radiation exposure in comparison to single-photon emission computed tomography (SPECT).
Cardiac PET tracers offer low radiation exposure and faster protocols but are limited to pharmacologic stress.
Myocardial blood flow is now routine and compliments cardiac PET perfusion imaging.
Risk stratification with cardiac PET perfusion imaging and myocardial blood flow offers precise decisions regarding therapies including intervention
Patient selection for cardiac MPI is critical for the proper use of the modality.
An emerging aspect of cardiovascular PET is the use in nonperfusion indications, especially with fluorodeoxyglucose imaging.
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Cardiac positron emission tomography (PET) has experienced rapid growth for cardiovascular imaging during the past several years. The mainstay, cardiac PET myocardial perfusion imaging (MPI), has emerged as an excellent noninvasive imaging modality for the diagnosis and risk stratification of patients with known or suspected coronary artery disease (CAD) with many important differences compared to single-photon emission computed tomography (SPECT) imaging. Cardiac PET MPI offers outstanding diagnostic accuracy, along with high image quality, low radiation exposure, and rapid protocols, and it is the noninvasive gold standard for measuring myocardial blood flow (MBF). Cardiovascular PET is becoming an important tool for nuclear cardiologists to consider not only for perfusion imaging, but also for a growing number of other indications, primarily with fluorine-18 fluorodeoxyglucose (FDG), such as assessing myocardial viability, inflammation (cardiac sarcoid) and infection imaging for cardiac device infection, and lead infection and endocarditis, as discussed in Chapters 22, 24, and 25. Its role in nuclear cardiology has expanded with the increased and continuous availability of PET radiopharmaceuticals and PET camera systems (see Chapters 3 and 4 on radiopharmaceuticals and instrumentation). This chapter will review the principles of cardiovascular PET, data on diagnostic accuracy, image quality, radiation exposure, indications, and addition of MBF for MPI, as well as exciting new nonperfusion applications. Protocols for cardiac PET MPI will be described as well.
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PRINCIPLES OF CARDIAC PET
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PET imaging provides excellent temporal and spatial resolution of radioactive atoms as they decay. A PET radioactive tracer, which has been designed or selected to be taken up preferentially in the organ of interest, is injected into the patient. After it reaches the target organ, the positrons emitted as the radioactive agent decays collide with nearby electrons (Fig. 10-1). The resulting collision causes annihilation of both an electron and a positron, creating a high-energy discharge of 1.02 MeV. This energy is split into two gamma rays of 511 keV energy, which are emitted at approximately 180 degrees from each other. For image collection, multiple detectors encircle the patient; absorption from both emissions simultaneously occurs, and events that are at 180 degree are considered “true” and used for image re-construction. The distance to the annihilation event impacts the ultimate image quality. The processing of these simultaneous events ...