Cardiac positron emission tomography

Positron emission tomography (PET) is a non-invasive radionuclide imaging technique that, when used with appropriate radiotracers and kinetic models, permits absolute quantitative measurements of myocardial perfusion, metabolism and receptor density in vivo. Assessment of the coronary vasodilator reserve (ratio of hyperaemic to baseline myocardial blood flow) has provided insights into both the functional significance of coronary artery stenoses in patients with coronary artery disease and abnormalities of the coronary microcirculation in patients with different cardiomyopathies. The use of PET to identify myocardial viability (by preserved uptake of ¹⁸F-fluoro-deoxy- glucose) allows the localisation of hibernating myocardium and the quantification of infarct size in patients with coronary artery disease. Measurements of myocardial oxygen consumption using PET with oxygen-15 and ¹¹C-acetate have provided information on myocardial metabolism during ischaemia and myocardial stunning. Tracers and kinetic models have also been developed permitting investigation of the role of the cardiac autonomic nervous system in the pathophysiology of heart failure and arrhythmogenesis. The high spatial resolution of modern PET cameras and the validation of new tracers may provide further insights into cardiac pathophysiology, e.g. to assess the transmural distribution of myocardial blood flow and metabolism across the left ventricular wall.