Nuclear cardiology is an integral part of cardiovascular practice, with stress nuclear cardiology procedures accounting for more than one third of all stress tests performed by cardiologists and, until recently, sustaining growth rates approaching 20% per year. This chapter provides a synopsis of nuclear cardiology procedures and the published evidence of their role in the diagnosis and risk assessment of patients with suspected or known coronary artery disease (CAD). In this chapter, CAD refers to the presence of an obstructive stenosis, in contradistinction to coronary atherosclerosis, which denotes the presence of any atherosclerotic plaque in the coronary arteries.
Historical Perspectives in Nuclear Cardiology
The Anger scintillation camera, the imaging device used today for the vast majority of all nuclear cardiology procedures except positron emission tomography (PET), became clinically available in the late 1960s. By providing dynamic images of the cardiac distribution of radioactivity, this camera marked the beginning of clinical nuclear cardiology. The commercial availability in 1976 of thallium-201 (201Tl) initiated the broad application of clinical myocardial perfusion scintigraphy. Two-dimensional planar 201Tl imaging was quickly shown to be useful for detection of CAD and, in the early 1980s, was demonstrated to be highly valuable in risk stratification of the CAD patient. Also in the early 1980s, single-photon emission computed tomography (SPECT), using a rotating Anger camera detector, became widely available, increasing the ability to localize and quantify regional myocardial perfusion defects. In 1990, technetium-99m (99mTc)-sestamibi was approved for use in the United States, followed shortly thereafter by another 99mTc-based agent, 99mTc-tetrofosmin. The higher myocardial count rates of the 99mTc agents made it possible to perform electrocardiogram (ECG)-gated SPECT myocardial perfusion imaging (MPI) by obtaining images from the different parts of the cardiac cycle (gated SPECT). By the late 1990s, the widespread availability of dual-detector cameras and dramatic increases in speed of computer systems allowed gated SPECT MPI to become a common clinical routine.1 By 2003, >90% of SPECT MPI used gated SPECT, providing routine objective clinical assessments of rest and stress myocardial perfusion and function. Radionuclide angiography played a prominent role in nuclear cardiology in decades past, but by the 1990s, the use of this modality was largely replaced by echocardiography. Gated SPECT MPI now makes up >95% of all nuclear cardiology procedures and thus is the primary focus of this chapter.
The American College of Cardiology (ACC)/American Heart Association (AHA)/American Society of Nuclear Cardiology (ASNC) Guidelines for the Clinical Use of Cardiac Radionuclide Imaging provide a useful, comprehensive review of the recommendations for the use of nuclear cardiology techniques.2 Importantly, in 2009, the Appropriate Use Criteria of the ACC and ASNC were revised, providing a summary of scenarios in which the use of SPECT or PET MPI is evaluated as indicated, uncertain, or not indicated.3
Basic Concepts of Gated SPECT MPI
SPECT MPI is performed using a scintillation ...