Extent of myocardial damage in regions with reverse redistribution at 3 h and at 24 h on : Evaluation based on regional myocardial oxidative metabolism201: Evaluation based on regional myocardial oxidative metabolismTl SPET: Evaluation based on regional myocardial oxidative metabolism

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Abstract

Summary

Reverse redistribution (RRD) of 201Tl is often observed in patients with recent myocardial infarction. However, the difference in the extent of myocardial damage between regions with 3-h RRD and those with 24-h RRD remains unknown. Accordingly, we investigated RRD from the standpoint of myocardial oxidative metabolism. Carbon-11 (11O acetate dynamic myocardial PET scanning was performed at rest in 14 patients with recent myocardial infarction, and the clearance rate constant (Kmono) of 11C-acetate was calculated in 6–7 ROIs on the transaxial image in each patient using a monoexponential fit as an index of myocardial oxidative metabolism. Exercise 201Tl myocardial SPET was also performed. Ninety-two regions corresponding to the PET study were then classified based on the findings of transaxial 201Tl SPET imaging; that is, regions with reverse redistribution, regions with severely decreased 201Tl activity or no 201Tl activity on the 24-h delayed images, and regions with normal 201Tl activity throughout the study. Kmono in regions with reverse redistribution (0.051 ± 0.009 min-1) was significantly lower than that in regions with normal 201Tl activity throughout the study (0.066 ± 0.011 min-1) (P < 0.001) but significantly higher than that in regions with severely decreased or no 201Tl activity on the 24-h delayed images (0.037 ± 0.003 min-1) (P < 0.001). Percent Kmono (i.e. Kmono in region with RRD/the mean of Kmono in all regions with a normal 201Tl SPET result) was significantly lower in the 3-h RRD regions (81.3 ± 6.3%) than in the 24-h RRD regions (87.6 ± 6.1%) (P < 0.05). Impairment of myocardial oxidative metabolism is observed in regions with RRD, suggesting that RRD corresponds to mild myocardial damage. Reverse redistribution on 24-h delayed images may indicate much milder myocardial damage compared with RRD on 3-h delayed images. (© 1998 Lippincott Williams & Wilkins)

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