1 東京都立大塚病院検査科Department of Clinical Laboratory, Tokyo Metropolitan Otsuka Hospital
2 東京都立大塚病院内科Department of Internal Medicine, Tokyo Metropolitan Otsuka Hospital
はじめに：Shear Wave Elastography（SWE）は，検査の習熟度や測定条件の違いにより差が生じることが知られている．今回，検査の精度向上を目的とし，測定条件および検者内・間評価法の信頼性について検討を行った．
対象と方法：対象は肝疾患非保有者6名．（平均年齢46.5±15.4歳，男性2名，女性4名）使用機器はキヤノンメディカルシステムズ社製Aplio300（探触子PVT-375BT）．超音波検査従事者5名が，剪断波速度（以下Vs）（m/s）を測定した．検討項目は，1）検者内・間の測定値のバラつき，2）一つのROIに対して測定ポイントを一つ置く方法と四つ置く方法による比較，3）仰臥位と30度程度の左側臥位との体位比較，4）測定回数による比較．信頼性の評価は級内相関係数（ICC）を，統計にはt検定をそれぞれ用いた．
結果：1）検者内ICC（1,1）は5人中4人で0.7以上，検者間ICC（3,5）は0.8であった．2）被験者6例中2例，検者間5例中1例において有意差を認めた．3）体位による有意差は認めなかった．4）1回測定値と3回測定平均値との間には有意差を認め，3回測定平均値と6, 9, 12回測定平均値との間には有意差を認めなかった．
考察：CV値が高値となった例では，肝測定断面やROIの置く位置が他例とは異なりこれらの測定条件の違いがVs値のバラつきに影響すると推測された．
結語：肝疾患非保有者においては，測定条件を統一し，一つの測定ポイント，仰臥位，3回測定の平均値を用いることで精度は保たれると考える．
Objective: The difference in results from shear wave elastography (SWE) could be caused by variations in degrees of measurements and procedure conditions. We aimed to improve the reliability and precision of SWE by defining the optimal measurement conditions and assessing the reproducibility among evaluators.
Subjects and Methods: Five sonographers measured shear wave velocity (SWV; m/s) in six persons without liver disease (mean age, 46.5±15.4 years; male, n＝2; female, n＝4) by ultrasound using an Aplio300 with a PVT-375BT probe (Canon Medical Systems). We calculated inter- and intraevaluator variations in the measured values and compared these values with set scores of 1 or 4 on the region of interest (ROI), in the supine position, with a slightly lateral decubitus position, and number of measurements. We used t-tests and intraclass correlation coefficients (ICCs) to statistically analyze the data.
Results: In four of the five sonographers, the ICC (1,1 and 3,5) of intra- and interevaluator variability, respectively, was ＞0.7. There was a significant difference in the data from two of the six evaluees and from one of the five evaluators. The position of the evaluee during the procedure did not differ significantly. Single measurements and the average of three measurements differed significantly, whereas the average of three, six, nine, and 12 measurements did not.
Discussion: A high coefficient of variation for liver sections under different test conditions or in selecting the ROI contributed to variations in SWV.
Conclusions: Results were more accurate for persons without liver disease under uniform test conditions, with single measurements, in a supine posture, and when three measurements were averaged.
Key words: shear wave elastography; ultrasonography; shear wave velocity
© 2021 一般社団法人日本超音波検査学会© 2021 Japanese Society of Sonographers
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This page was last modified on 2021-03-09T13:09:45.000+09:00
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