Thallium-201 as an agent for myocardial imaging studies

The increasing use of thallium-201 (201Tl) in myocardial imaging studies 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 injected dose was rapidly distributed to the healthy human myocardium, which is in agreement with previous reports. Apparent similarities exist between the transport of ionic thallium and potassium through cell membranes. Upon clinical use, myocardial perfusion scintigraphy is routinely carried out after i.v. administration of the agent. It is generally accepted that the rapid myocardial extraction of circulating 201Tl, during the initial 30 min. depends upon an unimpaired blood perfusion; whereas the prolonged uptake/redistribution during the next 3 h reflects myocardial viability. In the present paper, the reliability of 201Tl scintigraphy to disclose insufficient myocardial perfusion is illustrated by the examination of biological samples from patients, that were also studied by the classical coronary angiographic technique, the two methods showed an acceptable degree of agreement.