MYOCARDIAL VIABILITY ASSESSMENT WITH TECHNETIUM-99M-TETROFOSMIN AND TL-201 REINJECTION IN CORONARY-ARTERY DISEASE

Exercise-rest Tc-99m-tetrofosmin myocardial perfusion images with a 2-day protocol was compared to exercise-redistributionp-reinjection (TI)-T-201 images to assess the ability of Tc-99m-tetrofosmin to detect viable myocardium. Methods: We studied 25 patients with coronary artery disease and regional or global left ventricular dysfunction. Myocardial SPECT images with Tc-99m-tetrofosmin were obtained 10 min after injection during exercise and 1 and 3 hr after rest injection. Within 1 wk of the (TC)-T-99m-tetrofosmin study, exercise-redistribution-reinjection (TI)-T-201 SPECT imaging was performed. Results: Visual analysis demonstrated concordance between (TI)-T-201 and Tc-99m-tetrofosmin imaging for defect reversibility in 126 of 209 segments (60%), with initial defects on both exercise (TI)-T-201 and Tc-99m-tetrofosmin images. In the remaining discordant 83 segments (40%), 73 (88%) appeared nonreversible on Tc-99m-tetrofosmin imaging but were reversible on (TI)-T-201 imaging. Conclusion: On the basis of defect reversibility by visual analysis, exercise-rest Tc-99m-tetrofosmin imaging underestimates myocardial viability compared to (TI)-T-201 reinjection imaging. The identification of viable myocardium with both Tc-99m-tetrofosmin and (TI)-T-201 can be greatly enhanced to a similar degree if the severity of reduction in activity within nonreversible defects is considered. These two agents may provide comparable information about myocardial viability by quantitative analysis of defect severity.