DETECTION OF JEOPARDIZED MYOCARDIUM WITH TL-201 MYOCARDIAL PERFUSION IMAGING COMPARISON OF EARLY AND LATE REINJECTION PROTOCOLS

Reinjection of a second dose of Tl-201 before redistribution imaging h as significantly improved the ability of myocardial perfusion imaging to detect jeopardized myocardium. However, PET studies and the results from coronary artery angioplasty and bypass surgery indicate that TI- 201 studies still underestimate the number of ischemic areas at stress that represent viable myocardium. To determine whether an imaging pro tocol using an early reinjection of Tl-201 immediately after acquisiti on of the stress images would improve the detection of jeopardized myo cardium, 138 patients were studied with an early reinjection protocol and the incidence and magnitude of reversible defects were compared by SPECT to a second group of 143 patients who underwent the standard la te reinjection protocol. Two observers independently evaluated 19 stan dard myocardial segments by visual examination in each patient. They d etermined the presence or absence of reversible defects, and, when pre sent, their magnitude. The frequency of reversible defects always was less with early reinjection compared to the standard late reinjection; the difference reached statistical significance for one of the two ob servers (P < 0.05). It is concluded that early reinjection of Tl-201 i n myocardial perfusion imaging does not increase and may decrease the sensitivity of the study for jeopardized myocardium.