抄録
The purpose of this study was to investigate the clinical significance of the reverse redistribution (RR) phenomenon on technetium-99m (99mTc)-tetrofosmin myocardial single photon emission computed tomography (SPECT) performed at rest. Twenty-five patients underwent myocardial SPECT 3 weeks after the onset of acute myocardial infarction. Myocardial images were acquired at 40 min (early) and 4 h (delayed) after the injection of 740 MBq of 99mTc-tetrofosmin. The regional myocardial uptake of the tracer in 26 segments of the left ventricular (LV) wall was visually scored from 0 (no activity) to 3 (normal activity), and then the RR was defined as a decrease of more than 1 point in the activity score on the delayed image compared with that on the early image. Regions with an activity score of 3 on both the early and delayed images were defined as normal, and those with a score of 0 or 1 on the early image were considered to have a fixed defect. The regional myocardial 99mTc-tetrofosmin uptake and washout rate were also quantitatively assessed in each region. In addition, exercise stress electrocardiograph-gated SPECT with 99mTc-tetrofosmin was performed within 1 week of the rest study, and the percent count increase (%CI) during myocardial contraction in each corresponding region was studied. RR was observed in 18 of the 25 patients. The regional washout rate of 99mTc-tetrofosmin was significantly higher in the RR regions (45.0±3.8%) than in either the normal regions (36.4±4.1%, p<0.001) or in those with a fixed defect (39.7±3.9%, p<0.001). The %CI in the RR regions (10.4±10.4%) was significantly less than that in the normal regions (23.5±10.1%, p<0.001); however, no significant difference was found between the RR regions and those with a fixed defect (8.0±7.2%). In patients with acute myocardial infarction, the regions showing the RR phenomenon on 99mTc-tetrofosmin SPECT have severely impaired LV wall contraction after exercise. (Circ J 2003; 67: 830 - 834)
