TC-99M TEBOROXIME SCINTIGRAPHY - CLINICAL-EXPERIENCE IN PATIENTS REFERRED FOR MYOCARDIAL PERFUSION EVALUATION

In order to evaluate the clinical value of a new myocardial perfusion tracer, a series of 30 patients (25 male, 5 female, mean age 56 years) referred for thallium 201 stress/redistribution scintigraphy has been studied using stress/rest (n = 7) or rest/stress (n = 23) protocols with technetium 99m teboroxime (Cardiotec SQUIBB). In all cases coronary artery disease was known or highly probable, with a history of myocardial infarction in 18 cases. Medical treatment was not discontinued at the time of stress testing, and coronary angiography was available in 27 patients. Exercise tests for both tracers were carried out on a bicycle ergometer during the same day, and the levels of exercise achieved for the Tl-201 study were very similar to those achieved for Tc-99m-teboroxime. Studies performed in three planar projections were evaluated using a model with four territories: septal and anterior assumed to correspond to the left anterior descending artery, lateral and lateroposterior (left circonflex), inferior and posterior (right coronary artery) and apex. Classification of results was: normal, ischaemic, infarcted and infarcted with ischaemia. On comparison with the Tl-201 results, agreement was found in 86% (37/43) of normal regions and in 82% (63/77) of abnormal regions. Relative to documented coronary artery lesions (27 patients), sensitivity and specificity of Tl-201 and Tc-99m-teboroxime for exact correspondence between arteries and territories were respectively: Tl-201 : sensitivity 64%, specificity 60%; Tc-99m-teboroxime: sensitivity 62%, specificity 77%. These results, obtained in a given clinical context, indicate the ability of Cardiotec to evaluate myocardial perfusion with a significant saving in time, since the complete study duration (stress and rest) was: Tl-201, 4 h 35 min +/-21 min; Tc-99m-teboroxime, 1 h 52 min +/- 29 min. Nevertheless, the high liver uptake was responsible for 68% of non-evaluable inferior segments and the limited acquisition time makes the applicability of SPET questionable.