TL-201 FOR DETECTION OF MYOCARDIAL VIABILITY - COMPARISON OF EARLY POSTEXERCISE REINJECTION AND IMAGING WITH 4 AND 18-24 HOURS REDISTRIBUTION IMAGING

To evaluate the efficacy of an early Tl-201 reinjection and imaging pr otocol for reducing the need for conventional 4-hour or optimal 24-hou r redistribution imaging (RI) and detecting of myocardial viability, w e compared the results of early postexercise Tl reinjection and imagin g with those of 4- and 24-hour RI in 74 consecutive patients aged 55 /- 9 years (mean +/- SD) who were assessed for myocardial ischemia. On e millicurie of T1 was injected promptly after completion of the initi al postexercise imaging (PEX) and three additional sets of images were acquired 1, 4 and 18-24 h later. A total of 2,368 segments were evalu ated. On PEX, 390 (17%) segments showed defects, of which 287 (74%) sh owed enhanced T1 uptake at I-hour RI; 89 (23%) did not change and 14 ( 4%) showed reverse redistribution. Of the 103 persistent defects, only 27 (7%) showed further fill-in of T1; 62 (16%) segments showed revers e redistribution at 4-hour RI while at 18- to 24-hour RI 17 (4%) and 4 7 (12%) segments showed further fill-in of T1 and reverse redistributi on, respectively. Finally, after analysis of 4- and 18- to 24-hour RI, the diagnosis changed from myocardial necrosis to ischemia in only 2 (3%) patients. In conclusion, these results suggest that by eliminatin g the need for an additional delayed set of images for detection of my ocardial viability, this protocol reduces the total investigation proc edure, is more convenient for the patient, increases patient turnover and expedites the decision-making process.