TL-201 AS A TOOL FOR NONINVASIVE ASSESSMENT OF CORONARY-ARTERY DISEASE

Normal myocardial cells actively uptake the radioisotope Thallium-201 and its myocardial distribution Is a reflection of the existent regional coronary artery blood flow at the moment of the examination. Thallium-201 reaches quickly a high intracellular concentration and then leaves myocardial cells in a mean time of 4 to 8 h. In the presence of significant coronary artery disease, uptake and elimination rates of Thalium-201 are delayed in ischemic tissue, compared to normal tissue. This leads to regional differences in relative concentrations which allow to identify viable areas with insufficient coronary flow in conditions of vasodilatation induced by exercise or pharmacologic means. This phenomenon does not occur in the irreversibly damaged myocardium, and affected areas fail to uptake the radioisotope. Clinical applications of this test are: 1 - Search for coronary artery disease. 2.- Assessment of patients with known coronary artery disease. 3.- Evaluation of patients after revascularization procedures. 4.- Assessment of coronary risk before peripheral vascular surgery. 5. - Detection of viable myocardium. 6. - Assessment of coronary reserve in patients with angor and normal coronary vessels.