201Tl reinjection and late redistribution in the detection of viable myocardium

Nonreversible (NRD) myocardial perfusion defects following stress-rest (S/R) 201Tl studies may often be found in ischemic areas. 201Tl reinjection immediately following S/R scintigraphy and 24h (late) redistribution has been shown to identify late reversible defects (LRD) indicative of viable myocardium. Twenty two patients with CAD were studied. All subjects underwent S/R 201Tl (37MBq) 24h later (1 group). Six out of 22 patients had late scintigraphy without new doses of 201Tl. Ischemia was considered present when the poststress count density was less for more than 25% than the resting count density. Out of 29 NRDs. 15 segments exhibited late reversibility following 201Tl reinjection reflecting viability (II group). One out of 8 NRDs demonstrated late reversibility following late redistribution imaging (II group). Thus, 201Tl reinjection following S/R imaging appeared to be more effective in maximizing the detection of viable myocardium than late redistribution. It is equally useful in patients with NRD following S/R scintigraphy and no history of prior myocardial infarction (MI) or those who had MI.