title: Extent of myocardial damage in regions with reverse redistribution at 3 h and at 24 h on 201Tl SPET: evaluation based on regional myocardial oxidative metabolism.
abstract: 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 (11C) 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.
authors.affiliation: Third Department of Internal Medicine, Nagoya City University Medical School, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Ohte
authors.forename: T
authors.initials: T
authors.lastname: Hashimoto
authors.forename: A
authors.initials: A
authors.lastname: Iida
authors.forename: N
authors.initials: N
authors.lastname: Narita
authors.forename: S
authors.initials: S
authors.lastname: Akita
mesh_terms: D000085:Acetates / Q000378:metabolism; D000368:Aged; D002250:Carbon Radioisotopes; D005080:Exercise Test; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D010084:Oxidation-Reduction; D013794:Thallium Radioisotopes / Q000493:pharmacokinetics; D014055:Tomography, Emission-Computed; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D000085:Acetates; D002250:Carbon Radioisotopes; D013794:Thallium Radioisotopes