A dynamic study of intravenously administered 13NH3 in man with positron computed tomography

A whole body, multislice positron computed tomograph (POSITOLOGICA-II) was used to study the time course of concentration of 13N following intravenous administration of 13NH3 in the human heart, lungs and liver. Serial 30 seconds or 1 minute Positron-CT scans 6 to 7 minutes were performed immediately after intravenous administration of 13NH3 and time activity curves of the blood pool in the right and left ventricles, myocardium, lungs and liver were derived from these scans. The first scan gave cardiac blood pool images and these intracavitary 13N activity disappeared rapidly thereafter. On the other hand the myocardial 13N activity remained nearly constant throughout the period of observation and high quality cross-sectional images of the left ventricular myocardium were obtained. The patients with myocardial infarction revealed diminished accumulaton of 13N at the sites corresponding to the infaction. In the lung, there was a moderate uptake of 13N and this was washed out more slowly than in the intracavitary blood pool. The liver revealed a late uptake of 13N. These observations may represent transference of metabolized 13NH3. As the results, the present study clealy demonstrated the usefulness of 13NH3 as an imaging agent not only to the heart but also to the lungs and liver. (author)