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 vi able myocardium. Methods: We studied 25 patients with coronary artery disease and regional or global left ventricular dysfunction. Myocardia l SPECT images with Tc-99m-tetrofosmin were obtained 10 min after inje ction during exercise and 1 and 3 hr after rest injection. Within 1 wk of the (TC)-T-99m-tetrofosmin study, exercise-redistribution-reinject ion (TI)-T-201 SPECT imaging was performed. Results: Visual analysis d emonstrated concordance between (TI)-T-201 and Tc-99m-tetrofosmin imag ing for defect reversibility in 126 of 209 segments (60%), with initia l defects on both exercise (TI)-T-201 and Tc-99m-tetrofosmin images. I n the remaining discordant 83 segments (40%), 73 (88%) appeared nonrev ersible on Tc-99m-tetrofosmin imaging but were reversible on (TI)-T-20 1 imaging. Conclusion: On the basis of defect reversibility by visual analysis, exercise-rest Tc-99m-tetrofosmin imaging underestimates myoc ardial viability compared to (TI)-T-201 reinjection imaging. The ident ification of viable myocardium with both Tc-99m-tetrofosmin and (TI)-T -201 can be greatly enhanced to a similar degree if the severity of re duction in activity within nonreversible defects is considered. These two agents may provide comparable information about myocardial viabili ty by quantitative analysis of defect severity.