USEFULNESS OF REDISTRIBUTION IMAGES IN VIABILITY DETECTION AFTER ACUTE MYOCARDIAL-INFARCTION

We undertook this study to evaluate the importance of redistribution i mages in thallium 201 single-photon emission computed tomography (Tl-2 01 SPECT) assessment of myocardial viability after acute myocardial in farction. Stress-redistribution-reinjection Tl-201 SPECT was performed in 55 consecutive patients with recent (within 1 month) acute myocard ial infarction. The myocardium was divided into 16 segments and activi ty assessed visually with a score from 0 to 3 on stress-redistribution and stress-reinjection images. A defect was considered moderate if th e stress score was 2 and severe if the stress score was 0 or 1. All mo derate defects were considered viable, regardless of score on redistri bution or reinjection images. Severe defects were considered viable if they were reversible (improvement of 1 score) on redistribution or re injection images. Stress-redistribution and stress-reinjection images were visually analyzed and compared in terms of viability classificati on, On visual analysis, 461 segments (52%) were abnormal. One hundred eleven stress defects were moderate; of these, 28 were reversible on r einjection images only and 15 on redistribution images only. However, all of these segments were viable, regardless of the analysis chosen. Of 350 severe stress defects, 48 were reversible on reinjection and ir reversible on redistribution images, and 4 were reversible on redistri bution and irreversible on reinjection images. Therefore, in viability assessment, 48 segments were misclassified with stress-redistribution analysis, whereas only 4 segments were misclassified using stress-rei njection analysis. Although the usefulness of Tl-201 reinjection imagi ng is confirmed, redistribution images seem to be of little interest i n post-myocardial infarction viability assessment.