Radionuclide imaging with T1-201 is widely used for evaluating regional myocardial perfusion. Its value for diagnosing ischemic heart disease and estimating its extent has been well established. However, the distribution of myocardial blood flow can be assessed with this technique only qualitatively, and measurements of regional myocardial perfusion in terms of ml /min /gm myocardium are not possible. Such measurements can conceivably be made with the recently developed positron emission computed tomography (Positron-CT) [1, 2]. This new imaging modality permits noninvasive measurements of indicator tissue concentrations. Cross-sectional Positron-CT images of the heart quantitatively reflect regional tracer tissue concentrations and hence are comparable to autoradiography. They offer the capability of measuring in vivo tissue activity concentrations which previously has been possible only by in vitro counting of tissue samples. Combined use of this new imaging device with tracers of blood flow is likely to permit noninvasive measurements of regional blood flow in the human heart.
