Japanese
TitleXe-133ガス洗い出し法におけるバックグラウンドの補正と肺換気指標の選択
Subtitle原著
Authors蝦名昭男*, 井沢豊春*, 手島建夫*, 平野富男*, 今野淳*
Authors(kana)
Organization*東北大学抗酸菌病研究所内科
Journal核医学
Volume23
Number2
Page135-143
Year/Month1986/2
Article原著
Publisher日本核医学会
Abstract「要旨」肺の換気の異常を定量的に評価をするため, バックグラウンドの換気の指標に対する影響とその補正法の検討を行った. 準平衡洗い出し法で検査を行い, 補正前後に求めた指標の値からその影響を, 補正や算出の容易さおよび換気率(=VE min/(FRC+VT))との関係から換気の指標として適した指標について検討した. 正確に算出するためには, T1/2RやT1/2expは時間ごとの補正を要したが, 洗い出し開始120秒後までの総カウントを準平衡状態時と洗い出し開始120秒後の平均カウントの差で除して求めた指標T(A/H)は, 加算像での補正でよく, そのようにして算出した値は各時間ごとに補正して求めた値と一致した. 換気率との相関には差がなかったが, T1/2Rは, 統計変動の影響を受けやすく, T1/2expは近似曲線が洗い出し曲線と解離し, 指標として適さなかった. T(A/H)はT1/2Rとよく相関し, 補正や算出が容易で, 統計変動の影響が少なく指標として適すると思われた.
Practice臨床医学：一般
KeywordsXe-133, Semi-equilibrium, Background correction, Turn-over rate, Ventilation index.
English
TitleBack-ground Correction and Selection of Ventilation Indexes in Xenon Gas Ventilation Studies
SubtitleOriginal Articles
AuthorsAkio EBINA, Toyoharu ISAWA, Takeo TESHIMA, Tomio HIRANO, Kiyoshi KONNO
Authors(kana)
OrganizationDepartment of Medicine, The Research Institute for Chest Disease and Cancer, Tohoku University
JournalThe Japanese Journal of nuclear medicine
Volume23
Number2
Page135-143
Year/Month1986/2
ArticleOriginal article
PublisherTHE JAPANESE SOCIETY OF NUCLEAR MEDICINE
AbstractHow to treat the effect of back-ground countrate (BGC) on the ventilation indexes (VI) in the ventilation studies in the lungs has been given little attention to and no difinite method to correct the BGC has been established. The purpose of this study was to assess the effect of BGC on the VI's and establish a reasonable and simple way to correct the BGC. Xe-133 gas was inhaled with a semi-equilibrium method and washed out with air. Three ROI's were made for BGC correction ; an entire chest (ROI 1), an area covering Xe-133 activity within lungs and its scatter (ROI 2), and an area over the lung alone (ROI 3). Firstly we estimated the BGC per matrix in the region between ROI 1 and ROI 2 in each frame data. By analyzing the washout curves on the whole lung region (ROI 3) and regional lungs between semi-equilibrium and 120 seconds after washout started, three different VI's were calculated ; real half time (T 1/2R), half time estimated from exponential curve fitting (T 1/2exp), and/or the area under the curve (A) divided by the difference in mean count rate during semiequilibrium (a) and at 120 second (c) after washout started (T(A/H)=A/(a-c)). True VI's were calculated after BGC correction in each frame data. There was no uniform correlation between the non-corrected VI's and true ones, respectively. Therefore, we had to correct BGC to calculate each of the three VI's exactly. There were statistically significant correlations between 'turn-over rate' (=VE min/(FRC+VT)) and any of the true VI's calculated from the overall lung area (r=-0.8). T 1/2R could hardly be estimated in regional lungs in patients with chronic obstructive lung disease. T (A/H) correlated better with T 1/2R (r=0.941) than T 1/2exp. T (A/H) calculated after BGC correction in 'A', 'a', and 'c' were equal to T (A/H) calculated after BGC correction on each frame. In conclusion, the best VI is T (A/H) calculated after BGC correction on 'A', 'a', and 'c'.
PracticeClinical medicine
KeywordsXe-133, Semi-equilibrium, Background correction, Turn-over rate, Ventilation index.

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