ラットを用いたジピリダモール負荷プラナー画像における 99mTc-tetrofosmin 摂取率: 摘出臓器の摂取率との比較

We studied how precisely images reflect tracer uptake .in the myocardium, and examined what degree technetium-99m-tetrofosmin (c-tetrofosmin) in the liver and gastrointestine gave the effect to a myocardial image. After administering dipyridamole and 99m Tc­ tetrofosmin to normal rats, we compared the myocardial uptakes obtained using a gamma camera with the actual uptakes in the excised organs. Methods : Thirty-seven rats were used. Following imaging the anterior view at 5, 10, 15, 30, 60 and 90 min after admini­ stration of the tracer, uptakes in the heart, lung, liver and blood were estimated with a well-type scintillation counter (WC) and represented as percentage of the injected dose per gram of tissue (%ID/g). The regions of interest (ROis) were placed on planar images (PI) and the uptake in each organ was estimated as percentage of the injected dose per pixel (%ID/pixel). The ratios of PI-to-WC and heart-to-organ were also evaluated. Results : Cardiac uptake with WC was 1.688%± 0.395% at 10 min post-injection. On the other hand, that with PI was 1.855%±0.965% at 10 min post-injection. There were particularly great differences from 15 min post-injection between both measurements (PI/WC ratio : about 1.2 times). Pulmonary uptake with WC was the maximum at 15 min (0.861%± 0.387%) post-injection, and there was. hardly a variation in the activity later than 15 min. However, PI measurement showed the maximum value at 15 min (0.777%±0.163%), and decreased gradually. Hepatic uptake with WC was the maximum at 5 min (1.545%±0.563 %), and rapidly decreased. On the other hand, PI measurement showed higher value than WC as" the whole. Conclusion : Pl measurement showed higher uptakes in each organ than WC measurement. There were great differences between both measurements, at late phase particularly. As one of these causes, it was considered that the decrease of activity in blood was different from that in each organ with increasing time