EARLY POSTEXERCISE TL-201 REINJECTION AFTER SUBLINGUAL NITROGLYCERIN AUGMENTATION - EFFECTS ON DETECTION OF MYOCARDIAL-ISCHEMIA AND OR VIABILITY/

Background: Thallium-201 ((TI)-T-201) reinjection after conventional r edistribution imaging is a standard procedure, resulting in enhanced ( TI)-T-201 redistribution which is compatible with viable myocardium. A lthough this method significantly improves identification of viable my ocardium, it increases the investigation time by approximately I h. Th us, this technique is suboptimal from the standpoint of patient conven ience, since its routine performance may be impractical in a high-volu me nuclear medicine laboratory. Hypothesis: This study was undertaken to evaluate the efficacy of an early (TI)-T-201 reinjection and imagin g protocol in combination with sublingual nitroglycerin, to detect myo cardial ischemia and/or viability, and to reduce the need for conventi onal (4 h) redistribution imaging. Materials and Methods: In this stud y, 62 consecutive coronary patients, referred for the detection of pos sible myocardial ischemia and/or viability, were involved (mean age 55 years, range 41-70). Of those, 50 had previous angina attacks, with 4 2 having a history of previous myocardial infarction; 10 patients had coronary artery bypass grafting; and the remaining 2 had atypical ches t pain. Immediately after the completion of the initial postexer-cise imaging, 0.3 mg sublingual nitroglycerin followed by the reinjection o f Im Ci of (TI)-T-201 were administered, and two further sets of image s were acquired 1 h and 4 h later Results: In each set of images, a to tal of 496 segments were analyzed. On postexercise imaging, 305 (61%) segments demonstrated defects of which 198 (65%) showed enhanced thall ium uptake, 97 (32%) did not change, and 10(3%) showed reverse redistr ibution on 1 h reinjection imaging (IRI). Of the 97 persistent defects , only 17 (6%) showed fill-in of (TI)-T-201 on 4 h redistribution imag ing (CRI), while 12 (4%) segments showed reverse redistribution. On th e other hand, after analyzing the 62 patients of the 1 h IRI, 17 (27%) remained unchanged while in only 1 patient (6%) of 17 the diagnosis c hanged from myocardial necrosis to ischemia after analysis of the 4 h CRT. Conclusion: These results indicate that early postexercise reinje ction of (TI)-T-201 in combination with sublingual nitroglycerin follo wed by 1 h image acquisition may prove useful for a comprehensive and convenient assessment of myocardial ischemia and/or viability.