Assessment of Myocardial Perfusion by PET

Abstract

Several tracer approaches have been proposed for the assessment of myocardial perfusion with positron emission tomography (PET) in the clinical setting. These include nitrogen-13 (13N) labelled ammonia, oxygen-15 (15O) labelled water, rubidium-82 (82Rb) and potassium-38 (38K). These tracers require a local cyclotron for production, except for 82Rb which may be delivered directly to the patient from an on-site generator. There are two specific clinical applications of PET that have been proposed for the evaluation of patients with coronary artery disease (CAD) [1-3]. The first is the noninvasive detection of CAD and estimation of the severity of the disease. This is performed using a PET perfusion agent at rest and during pharmacologic vasodilation. A unique application of PET is the noninvasive calculation of absolute regional myocardial perfusion at rest and during vasodilation in humans using [15O]water or [13N]ammonia. However, most centers rely on the qualitative interpretation of 82Rb or [13N]ammonia images for the detection of CAD and the assessment of its severity. The second clinical application of PET is the assessment of myocardial viability in CAD patients with left ventricular dysfunction. The most common approach is to determine whether metabolic activity assessed by 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) is preserved in regions with reduced perfusion, thus indicating tissue viability.