Teboroxime, sestamibi and thallium-201 as markers of myocardial hypoperfusion: comparison by quantitative dual-isotope autoradiography in rabbits.

The scintigraphic assessment of myocardial hypoperfusion depends on the ability of imaging agents to delineate flow disparities. Accordingly, we compared the differential uptake of teboroxime, sestamibi and 201Tl in normal and hypoperfused myocardium using quantitative dual isotope autoradiography. Rabbits with acute coronary occlusions (n = 29) received dual isotope injections of teboroxime 201Tl or sestamibi 201Tl or single isotope tracer injections. A group of sham-operated controls (n = 15) received teboroxime and/or 201Tl. Multiple 30-mu short axis slices were collected from each heart and mounted on x-ray film along with tissue standards to independently generate separate 99mTc and 201Tl autoradiographs. Teboroxime and sestamibi produced greater normal-to-defect activity contrast than 201Tl in each dual isotope heart (range 8.4-48.9 [teboroxime] versus 2.6-12.3 [201Tl], p < 0.02 and 4.5-10.4 [sestamibi] versus 3.6-7.3 [201Tl], p < 0.03). Similar profiles were obtained in the single isotope hearts. Teboroxime produced larger autoradiographic defects than 201Tl in the dual-isotope hearts [16.0% +/- 5.6% (teboroxime) versus 12.9% +/- 5.3% (201Tl) of the LV, p < 0.02]. We conclude that the 99mTc-based perfusion agents teboroxime and, to a lesser extent, sestamibi, delineate hypoperfused myocardium more clearly than 201Tl. Teboroxime detects the largest area of hypoperfusion and may provide the most accurate assessment of myocardium at risk.