TL-201 REST-REINJECTION AND IODINE-123-MIHA IMAGING OF MYOCARDIAL-INFARCTION - ANALYSIS OF DEFECT REVERSIBILITY

Rest SPECT imaging with [I-123]-16-iodo-3-methylhexadecanoic acid (MIH A) frequently shows an increased level of uptake in areas with irrever sible defects on exercise Tl-201 SPECT. Such mismatch patterns between flow (Tl-201) and metabolic (MIHA) tracers might correspond to areas with ischemic but viable myocardium misidentified by Tl-201 imaging. M ethods: Eighty-three patients with myocardial infarction underwent exe rcise SPECT Tl-201 with rest-reinjection and rest SPECT with MIHA. Def ect areas on the exercise images were reversible on MIHA but not on Tl -201 reinjection images that were determined visually. The presence an d extent of these areas were quantified from normalized uptake values for both tracers. Results: In areas with irreversible Tl-201 reinjecti on defects, MIHA detected exercise defect reversibility in 59% of pati ents. In areas with irreversible Tl-201 reinjection defects, the exten t of visually determined defect reversibility on MIHA scans was relate d to the quantified extent of areas with Tl-201 uptake greater than or equal to 50% of normal; the correlation, however, was weak. In 86% of patients, areas with greater than or equal to 50% Tl-201 uptake were larger than those that were reversible on MIHA. Conclusion: After myoc ardial infarction, rest SPECT with MIHA often enables visual detection of increased uptake in areas with irreversible Tl-201 reinjection def ects.