胃癌の深達度診断—超音波内視鏡検査

Depth Diagnosis of Gastric Cancer by Endoscopic Ultrasonography

要旨●超音波内視鏡（EUS）を用いた胃癌の深達度診断について，その基本的手法と実践的ポイントを解説した．細径プローブは早期胃癌，専用機は厚みのある上皮下腫瘍や進行胃癌に適する．早期胃癌の深達度診断では潰瘍瘢痕合併の有無により基準が異なり，第3層の断裂距離はESD難易度予測に重要である．描出不良は特に胃下部とUL0 I型で多く，技術的・解剖学的理由が関与していた．EUSにより内視鏡診断が修正された症例は2.7%で既報より減少したが，診断の限界例は残されており，さらなる精度の向上が求められる．

　This article explains the fundamental techniques and practical points for diagnosing the depth of gastric cancer invasion by endoscopic ultrasonography（EUS）. Miniature probes are suitable to use for early gastric cancer, whereas ultrasound gastrointestinal videoscopes are appropriate for thick subepithelial tumors and advanced gastric cancers. The criteria for determining the depth of invasion in early gastric cancer differ based on the presence or absence of ulcer scars, and identifying the disruption length within the third layer is critical for predicting the difficulty of endoscopic submucosal dissection. Poor visualization frequently occurs, especially in lesions located in the lower stomach and those classified as UL0-I type, due to technical and anatomical factors. The proportion of cases where EUS led to the modification of the endoscopic diagnosis was 2.7%, which is lower than the rate reported in previous reports. However, challenging diagnostic scenarios still persist, necessitating further enhancements in diagnostic accuracy.