Section 1: Current Concepts of Cardiovascular Pet Imaging: The New Paradigm: Introduction

INTRODUCTION

An important evolutionary advancement in the field of nuclear cardiology has been the introduction of cardiovascular positron emission tomography (PET) into mainstream clinical care. An extensive peer-reviewed literature spanning almost 30 years virtually shouts out a role for cardiac PET in a substantial proportion of patients historically assessed with single-photon emission computed tomography (SPECT) or not previously evaluable by nuclear cardiology techniques. The substantial and growing evidence base has led to several pivotal multisocietal guidelines,¹ position statements,² and consensus documents^3,4 on the role of PET imaging in cardiovascular disorders. The theme of this Introduction is that a contemporary nuclear cardiology laboratory will not be SPECT-only or PET-only, but that these two modalities will coexist, at least for the foreseeable future.⁵ The published data and clinical need together are moving toward a concept in which SPECT or PET will be a preferred test for definable presentations and clinical descriptors.

In the coming chapters of this book, all of the various applications of cardiovascular PET will be thoroughly explored. The purpose of the current section is to provide a vision for how SPECT and PET should and can coexist in a culture of high-quality patient-centered imaging while achieving space and workforce efficiencies.

A BRIEF HISTORICAL OVERVIEW OF THE ROLE OF SINGLE PHOTON IMAGING IN THE ASSESSMENT OF CORONARY ARTERY DISEASE

Cardiac radionuclide imaging had its birth in an era in which cardiologists were primarily focused on coronary artery disease (CAD). By the 1970s, multicenter studies had shown that patients with triple-vessel, left main, and proximal left anterior descending disease fared better if treated with revascularization compared to medical therapies available at the time. However, it was difficult to identify among the large number of patients with symptoms potentially indicating CAD those who needed invasive evaluation. Cardiac radionuclide imaging addressed that need, evolving newer and better approaches in hardware (first with rectilinear scanners,⁶ then with planar cameras,⁷ and by the mid-1980s with SPECT),⁸ tracers (thallium-201 followed by Tc-99m sestamibi and tetrofosmin), and quantitative software. With an almost singular focus on CAD, a voluminous literature established the value of SPECT myocardial perfusion imaging (MPI) as a gatekeeper to the catheterization laboratory for many patients with nonacute known or suspected CAD. SPECT MPI also found daily use for diagnosing CAD, for risk stratification, and for assessing likelihood of viability of dysfunctioning myocardium. Figure S1-1 illustrates schematically how SPECT became positioned as a pivotal test for almost all patients except those who could perform a diagnostic-level treadmill exercise test that was adequate for decision making or who were deemed to be appropriate for direct referral to coronary angiography. Levin et al⁹ used only Medicare data to show that SPECT MPI grew from 63.4 tests per 1000 beneficiaries in 2001 to 88 tests per 1000 beneficiaries in 2006, an impressive rate of growth that propelled SPECT MPI ...