@techreport{oai:kanazawa-u.repo.nii.ac.jp:00046876,
 month = {Mar},
 note = {心筋血流製剤における肝臓,肺臓および腸管の集積が画像から算出した心筋摂取率に及ぼす影響を検討するために,^<99m>Tc-tetrofosminを投与したラットをガンマカメラでプラナー像(以下,PI)で撮像し,画像から得られた各臓器の摂取率と,摘出臓器(心臓,肺臓,肝臓,血液および腸管)をウェル型シンチレーションカウンタ(以下,WC)で測定した摂取率の値を経時的に比較した。WCによる心臓摂取率は,投与30分後(1.671%±0.306%)まで増加し,その後緩やかに減少した。一方,PIによる摂取率は,投与15分後(1.814%±0.518%)に最大値となり,両者の差は投与10分後(PI/WC比:約1.6)に最大となった。WCによる肺摂取率は投与15分後(0.870%±0.312%)から次第に減少したが,PIによる摂取率は10分後(1.139%±0.376%)で高値を示し,その後ほとんど変化を認めなかった。またWCによる肝臓摂取率は投与5分後(0.768%±0.193%)から30分後(0.692%±0.273%)までほとんど変化を認めず,その後次第に減少したが,PIによる摂取率はWCに比し,10分後(1.949%±0.596%,PI/WC比:約3.3倍),15分後(1.845%±0.642%,PI/WC比:約2.3倍)で高値を示した。WCによる心臓/臓器比はいずれも経時的に増加したが,PIでは経時的変化が少なく,低値であった。PIによる十二指腸と上部小腸の摂取率は投与後10分(1.228%±0.602%,2.245%±1.936%)で最大となり,各腸管壁とその内容物の摂取率の割合は,十二指腸,小腸ともに90%以上が肝臓から排泄された内容物によるものであった。以上より,心臓,肺臓,肝臓の摂取率は,いずれもWCによる値に比べPIでは有意に高値を示した。特に投与後早期で両者の差は大となり,投与10分後では,PIによる心臓の摂取率とWCによる摂取率との間に大きな乖離がみられた。PIから算出された摂取率は必ずしも真の値を正確に表しておらず,心臓に隣接する肝臓,腸管などの高集積による散乱線の関与が大きいと思われた。, It's reported that the duodenum and the small intestine of the activity excreted from the liver and gallbladder can lead to interference with the myocardial uptake. To study how precisely images reflect tracer uptake in a myocardium, as fundamental experiment to examine the influence that accumulation of the liver and alimentary tract (except esophagus) of the activity excreted from the liver gave to the myocardium image in the technetium-99m myocardium perfusion tracer, we administered ^<99m>Tc-tetrofosmin (following, Tetrofosmin) to a normal rat and compared with measured value obtained by a gamma camera and an actual survey value after the organs extraction. Methods : Thirty-three rats were measured for 5, 10, 15, 30, 45, 60, 90 and 120min after the administration of Tetrofosmin. The accumulated rates for the myocardium, the lung, the liver, the duodenum, the small intestine, the rectum and the blood with a well-type scintillation counter (WC) were assessed as a percentage of t he injected dose per gram of tissue (%ID/g). The accumulated rates for each organ with the planar imaging (PI) were assessed as a percentage of the injected dose per pixel (%ID/pixel) establishing regions of interest (ROIs) in each organ. The accumulated rates for each organ, the PI-to-WC ratio and the heart-to-organ ratios calculated by PI and WC were compared. Results : The accumulated rate for the heart with WC increased until 30 min (1.671%±0.306%) after the injection, and subsequently decreased. On the other hand, peak of the accumulated rate with PI was shown at 15 min (1.814%±0.518%) after the injection. Particularly a difference of both was higher in 10 min (PI/WC ratio : about 1.6 times) of the early phase. The accumulated rate for the lung with WC was maximum at 15 min (0.870%±0.312%) after the injection. The accumulated rate with PI, however, showed the maximum value at 10 min (1.139%±0.376%), and a variation of the accumulated rate was hardly recognized 10 min later. The accumulated rate for the liver with WC was hardly shown a marked variance from 5min (0.768%±0.193%) to 30min (0.692%±0.273%), and a tendency of decrease was showed slowly. On the other hand, the accumulated rate with PI was more highly than that with WC in the whole, and high values were showed in 10 min (PI/WC ratio : about 3.3 times) and 15 min (PI/WC ratio : about 2.3 times) in particular. The accumulated rate for the duodenum and the upper small intestine was maximum in 10 min (1.228%±0.602%, 2.245%±1.936%) after the injection, and approximately 90% of ^<99m>Tc-tetrofosmin were the duodenum excrements. Conclusion : The accumulated rates for each organ with PI were showed higher than that with WC. The difference of both, particularly, was stronger in early phase after the injection. The accumulated rate for the heart with PI was shown significant higher than that with WC at 10 min. The interference of Compton scatter from the liver, duodenum and small intestine was suggested as one of these causes., 研究課題/領域番号:10670836, 研究期間(年度):1998-1999, 出典：「核医学的手法による動物モデルを用いた臓器血流の定量化の研究: γ線の吸収散乱因子」研究成果報告書　課題番号10670836
  (KAKEN：科学研究費助成事業データベース（国立情報学研究所）)
　　　本文データは著者版報告書より作成},
 title = {核医学的手法による動物モデルを用いた臓器血流の定量化の研究: γ線の吸収散乱因子},
 year = {2000}
}