消化管粘膜下腫瘍におけるEUSの基本と近年の進歩

Basics and recent advances of EUS in gastrointestinal submucosal tumors

要旨

消化管粘膜下腫瘍（SMT）は日常診療でしばしば遭遇する疾患であり，EUSが鑑別診断に有用である。本稿では，EUSによるSMTの描出のコツと診断，近年の進歩について述べる。EUSの機器選択では，細径超音波プローブと超音波内視鏡専用機の特徴を理解し，適切に使い分け，描出方法の基本を知る必要がある。SMTをエコーで診断するためには，腫瘍の大きさ，内部エコー像，発生部位が重要であり，臓器別の特徴を理解することが重要である。超音波専用機を用いたEUS-FNAでは，適切な手技と穿刺針の選択が診断能向上に寄与する。近年の進歩として，造影ハーモニックEUS（CH-EUS）やdetective flow imaging，EUS下needle-based confocal laser endomicroscopy（nCLE）が質的診断に有用であることが報告されており，人工知能（artificial intelligence：AI）を用いた画像解析により診断能向上が期待される。

　Submucosal tumors (SMT) are frequently encountered in daily clinical practice and require a differential diagnosis. Endoscopic ultrasound (EUS) has been reported to be useful in the differential diagnosis of SMT. In this article, we will explain tips and tricks for diagnosing SMT using EUS, as well as recent advances in this field. When selecting an EUS device, it is necessary to understand the characteristics of the small-diameter ultrasound probe and dedicated ultrasound endoscope equipment and use them appropriately. To diagnose a SMT using echocardiography, it is important to understand the tumor size, internal echo images, site of occurrence, and organ-specific characteristics. Appropriate technique and needle selection contribute to improved diagnostic performance in EUS-FNA, which uses a dedicated ultrasound diagnostic device. Recent advances include contrast-enhanced harmonic EUS (CH-EUS), which has been reported to be useful for qualitative diagnosis; needle-based confocal laser endoscopy (nCLE) under detective flow imaging and EUS; and the use of artificial intelligence (AI). Regarding prospects, it is expected that diagnostic performance will improve through image analysis using AI.