Myocardial scintigraphy using 99m-Tc-methoxyisobutylisonitrile (Tc-MIBI): A full substitution of 201-Tl?

The results of selective coronary angiography, myocardial 201-Tl scintigraphy (stress and redistribution) and after 99m-Tc-methoxyisobutylisonitrile stress and rest injections (Tc-MIBI, Cardiolite, DuPont de Nemours, USA) were compared in 19 patients with manifest ischemic heart disease in identical three projections and after same ergometric load. 16 patients had significant stenoses of 1-3 main coronary arteries inclusive of left coronary artery main stem, insignificant stenoses (<50%) were present in the remaining 3 patients. Scintigraphic localizations of accumulation defects in both Tc-MIBI and 201-Tl stress scintigraphy were in agreement in 70.6% of evaluated left ventricular wall segments. A positive 201-Tl redistribution and rest-stress Tc-MIBI scintigraphic difference agreed in 52.6% of images of all three projections with verified accumulation defects. The sensitivity of ischemic area detection in reference to coronary angiography was nearly identical in 201-Tl (75%) and Tc-MIBI scintigraphy (81.2%). Better physical properties of 99m-Tc from the point of view of a gamma camera detection, a possibility to get markedly higher counting rate and sufficient accumulation of the radiopharmaceutical in the perfused myocardium enable to reach scintigraphic pictures with a high contrast after labelled Tc-MIBI injection, even in case of sequential impulse summation during heart cycle (gating). (author) 1 tab., 1 fig., 14 refs