Preliminary report of SPECT imaging with Tc-99m teboroxime in ischemic heart disease.

Tc-99m teboroxime (Cardiotec) is one member of a new class of radiopharmaceuticals, the BATO agents (boronic acid adducts of technetium dioxime). This agent is a small, neutral, lipophilic compound with a high myocardial extraction (approximately 85% to 90%), and its uptake in the heart is directly related to myocardial perfusion. Tc-99m teboroxime washes out rapidly from the heart, and its potential for SPECT imaging has therefore been questioned. Tc-99m teboroxime SPECT imaging was compared prospectively with thallium SPECT (20 of 20 patients) and coronary arteriography (17 of 20 patients) suspected of having coronary artery disease. In this small preliminary series, both Tc-99m teboroxime and thallium SPECT detected all abnormal patients (12 of 12) and predicted correctly the site of critical stenosis in 20 of 24 diseased arteries (83%). Tc-99m teboroxime SPECT was normal in 5 of 6 patients without evidence of disease. Several cases occurred of clearly different radiotracer distribution (not related to obvious artifacts) with teboroxime compared with thallium, and lesion size was significantly larger on teboroxime compared with thallium SPECT. The clinical significance of these differences is not yet clear. Tc-99m teboroxime SPECT is possible with imaging times less than half those of thallium SPECT. Though much work remains to be done, teboroxime, because of its unique kinetics, creates many new possibilities for the evaluation of ischemic heart disease.