Positron computed tomography for studies of myocardial and cerebral function.

Positron computed tomography is a noninvasive medical imaging technique. Biologically active, radiolabeled compounds are administered intravenously to patients and the distribution of the radioactivity is quantitatively measured. By using appropriate mathematical models and labeled compounds, quantitative measurements of local metabolism, blood flow and volume, protein synthesis, transport, receptor binding, drug kinetics, and concentrations can be obtained noninvasively. This technique goes beyond medical imaging; it allows local analytic assays of biochemical reactions. In the heart, the technique measures local blood flow as well as myocardial free fatty acid and glucose metabolism, and can clinically evaluate patients with ischemic heart disease or cardiomyopathies. In the brain, positron computed tomography can be used to examine alterations in blood flow and metabolism including ischemia and degenerative disorders (Huntington's disease and Alzheimer's disease), cerebral tumors, and epilepsy. In normal persons, positron computed tomography shows cerebral activations resulting from physiologic stimulation (auditory and visual).