The role of positron emission tomography in cardiology

Abstract

Positron emission tomography (PET) imaging has become established as a diagnostic tool in cardiovascular imaging. The most important clinical applications in cardiology are the assessment of myocardial perfusion and metabolism. Tracers used for perfusion imaging include15O-labelled water,13N ammonia and82Rb. For metabolic studies,11C palmitate,11C acetate and18F-2-fluoro-2-deoxyglucose (FDG) are used. Studies of myocardial metabolism are of particular value in the assessment of myocardial viability in patients with ischaemic heart disease and impaired left ventricular function. Restoration of blood flow to regions of underperfused but viable myocardium (‘hibernating myocardium’) can improve left ventricular function in this patient-group. PET imaging with FDG provides positive predictive values of approximately 72%, and negative predictive values of around 83% for improvement of left ventricular function following revascularization in these patients. Other applications of PET in cardiology include the assessment of sympathetic receptor density and distribution in the heart. The use of PET imaging is currently limited mainly by its high cost and low availability, but low-cost PET systems are being developed and coincidence imaging with gamma cameras is another developing alternative to PET. Other imaging techniques such as dobutamine stress echocardiography, thallium reinjection imaging, SPECT and MRI are also continuing to improve and have to be compared to PET imaging. The future role of PET in cardiology is expected to increase as a result of developments in the technology and the availability of lower-cost systems.