| Japanese |
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| Title | 99mTc - ECD SPECTにおける2分割投与法 (split - dose法) の問題点と改良法 |
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| Subtitle | 原著 |
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| Authors | 小田野行男*, 大久保真樹**, 高橋誠*, 野口栄吉*, 大滝広雄*, 柴木充朗*, 笠原敏文*, 羽田野政義* |
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| Authors(kana) | |
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| Organization | *新潟大学医学部放射線科, **新潟大学医療技術短期大学部診療放射線技術学科 |
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| Journal | 核医学 |
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| Volume | 34 |
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| Number | 5 |
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| Page | 323-328 |
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| Year/Month | 1997/5 |
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| Article | 原著 |
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| Publisher | 日本核医学会 |
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| Abstract | 「要旨」中枢性疾患など11症例を対象に, 2分割投与99mTc-ECD脳血流SPECTにおいて, 投与放射能量の違い(投与比)によりSPECTカウントを補正する方法の妥当性を検討した. 1:1から1:4の割合で2分割(D1:D2)した99mTc-ECDを連続した2回の安静状態で静注してSPECT撮像し, 1回目のSPECTカウントC1と2回目の正味SPECTカウントC2(=2回目のSPECT像-1回目のSPECT像)を投与比で補正したものとの割合K(=C2/C1×D1/D2)を, 脳内各領域で求めた. 2回の安静状態であることからK=1になることが期待されたが, 被検者によっては1から大きくはずれる場合が見られた. K=1からのずれは平均で10.4±4.9%(平均誤差)となった. したがって, 何らかの負荷を加えた場合に有意な脳血流の変化を検出するためには, 平均誤差の2倍以上の変化を有意とすると, 安静時SPECTカウントの約20%以上の変化が必要であると考えられた. 故に脳血流の増減が少ない負荷検査において, その変化を投与比補正法で評価することは困難であると思われた. 上記の誤差要因として, 99mTc-ECDの投与量の測定誤差, 血管内残存, 肺集積, 血中における代謝の影響およびSPECT画像処理行程などが考えられる. そこで, K=1からの誤差(ずれ)がより小さくなる新しい方法を考案した. この方法では2回のSPECTカウントC1, C2を脳内のある参照領域で規格化し, その変化率Kreferenceを評価する. 今回は小脳または後頭葉を参照領域として変化率(Kcbll, Kocci)を求めた. 2回の安静状態で調べると, 被検者ごとのKcbll, Kocciはともに1に近くなり, 平均誤差も減少して本法の妥当性が認められた. この方法は, Diamox負荷など参照領域の脳血流自体が変化する場合の評価には問題があるが, 起立負荷や手指運動負荷などの負荷検査には有用と考えられた. |
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| Practice | 臨床医学：一般 |
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| Keywords | 99mTc-ECD, Split-dose, SPECT. |
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| English |
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| Title | A Limitation of the Split - Dose Method for Evaluating rCBF Changes Using 99mTc - ECD and SPECT |
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| Subtitle | Original Articles |
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| Authors | Ikuo ODANO*, Masaki OHKUBO**, Makoto TAKAHASHI*, Eikichi NOGUCHI*, Hiro OHTAKI*, Mitsurou SHIBAKI*, Tosifumi KASAHARA*, Masayoshi HATANO* |
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| Authors(kana) | |
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| Organization | *Department of Radiology, Niigata University School of Medicine, **Department of Radiological Technology, College of Biomedical Technology, Niigata University |
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| Journal | The Japanese Journal of nuclear medicine |
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| Volume | 34 |
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| Number | 5 |
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| Page | 323-328 |
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| Year/Month | 1997/5 |
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| Article | Original article |
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| Publisher | THE JAPANESE SOCIETY OF NUCLEAR MEDICINE |
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| Abstract | [Summary]The purpose of the study is to validate the split-dose method corrected with dose ratio of 99mTc-ECD for brain perfusion scan. A dose of 600 MBq of 99mTc-ECD was divided into two with various dose ratios from 1:1to1:4, and injected to eleven patients with various cerebral diseases. A lesser dose of 99mTc-ECD was injected under a control state for the first SPECT scan, and 15min SPECT scan was performed 10min after injection with a triple-head high resolution gamma camera. After the scan, the other dose of 99mTc-ECD was injected under the same control state and the second SPECT scan was performed as same as above. A ratio of the activity of the first scan to the net activity of the second scan corrected by dose ratio, defined as K, was measured in brain regions of each subject. Expected value of K was 1, but the value was distributed with large variations in each subject. The mean%error of the K value was 10.4+-4.9%. Hence it is considered that activity changes by more than 20% from the control values should be required to detect a significant rCBF change in an activation SPECT study. Then, we proposed a new method in which the activity of both two SPECT scans was normalized by cerebellar or occipital activity and compared. The ratio obtained by the proposed method came closer to 1 with less variations and with less mean%error in comparison with those of K value obtained by the dose-correction method. Although the proposed method has a limitation in the use of an activation study loaded with Diamox, it may be useful to evaluate an alteration of rCBF in the study such as postural testing or finger-moving test. |
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| Practice | Clinical medicine |
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| Keywords | 99mTc-ECD, Split-dose, SPECT. |
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