消化管疾患に対するEUS検査法

EUS for Gastrointestinal Diseases

要　旨

EUSは消化管腫瘍に対する実臨床に欠かせない診断モダリティであり，先端部に超音波振動子を装着したEUS専用機と，通常の内視鏡と併用できる細径プローブに分けられる。利便性では細径プローブが勝るが，専用機は電子走査式となったことによりエラストグラフィーなど超音波観測装置で使用されている種々のアプリケーションが利用可能となり，診断精度の向上が期待される。しかし消化管EUSの基本はBモード画像であり，消化管壁層構造を適切に描出した超音波断層像をもとに，上皮性腫瘍の深達度や消化管粘膜下腫瘍の質的診断を行うことが基本である。

　EUS is a diagnostic modality that is indispensable in clinical practice for gastrointestinal tumors. There are two types of EUS, one is an echoendoscope which is a dedicated machine equipped with an ultrasonic transducer at the tip and the other is a probe type that can be used in combination with a normal endoscope. Although the small-diameter probe is superior in terms of convenience, the echoendoscope makes it possible to use various applications such as elastography, and it is expected that the diagnostic accuracy will be improved. However, the basis of gastrointestinal EUS is clearly visualized B-mode image, and the depth of tumor invasion and qualitative diagnosis of submucosal tumor are made based on the ultrasonic tomographic image that appropriately depicts the gastrointestinal wall layer structure.