TL-201 AS AN AGENT FOR MYOCARDIAL IMAGING STUDIES

The increasing use of thallium-201 (201Tl) in myocardial imaging studi es during the last two decades, has justified a re-examination of the metabolism of this metal compound. It was found that about 4% of an in jected dose was rapidly distributed to the healthy human myocardium, w hich is in agreement with previous reports. Apparent similarities exis t between the transport of ionic thallium and potassium through cell m embranes. Upon clinical use, myocardial perfusion scintigraphy is rout inely carried out after iv administration of the agent. It is generall y accepted that the rapid myocardial extraction of circulating Tl-201, during the initial 30 min, depends upon an unimpaired blood perfusion ; whereas the prolonged uptake/redistribution during the next 3 h refl ects myocardial viability. In the present paper, the reliability of Tl -201 scintigraphy to disclose insufficient myocardial perfusion is ill ustrated by the examination of biological samples from patients, that were also studied by the classical coronary angiographic technique, th e two methods showed an acceptable degree of agreement.