大野 栄三郎¹, 廣岡 芳樹², 川嶋 啓揮¹, 石川 卓哉¹, 藤城 光弘¹

Eizaburo OHNO¹, Yoshiki HIROOKA², Hiroki KAWASHIMA¹, Takuya ISHIKAWA¹, Mitsuhiro FUJISHIRO¹

¹名古屋大学大学院医学系研究科消化器内科学, ²藤田医科大学肝胆膵内科学講座

¹Department of Gastroenterology and Hepatology, Nagoya University Graduate School of Medicine, ²Department of Liver, Biliary Tract and Pancreas Diseases, Fujita Health University

キーワード : endoscopic ultrasound, pancreatic cystic neoplasms, contrast-enhanced endoscopic ultrasound, endoscopic ultrasound-fine needle aspiration, intraductal papillary mucinous neoplasm

超音波内視鏡（endoscopic ultrasonography: EUS）は，高い空間分解能で膵臓全体の観察を可能とし，膵病変の診断で重要な役割を果たすモダリティである．近年，超音波，コンピューター断層撮影（CT），磁気共鳴画像法などの画像診断法の進歩により，膵嚢胞性疾患（pancreatic cystic lesions: PCL）の検出率が増加している．EUSは，PCLの検出と評価に不可欠な診断法として認知されている．EUSには，詳細な（高分解能）画像診断法と，病理学的診断またはバイオマーカー評価のための超音波内視鏡下穿刺吸引生検（EUS-guided fine needle aspiration: EUS-FNA）を用いた膵嚢胞液の採取するためのツールという，2つの重要な役割がある．近年，PCLの鑑別診断あるいは悪性度評価に対する造影EUS，および針を通して膵管内構造を観察するための，細径共焦点レーザー内視鏡と呼ばれる新しい画像法の有用性が報告されている．超音波画像法で表示されるPCLの形態学的特徴や，日常の診療におけるEUSの利点や限界を理解することが必要である．

Endoscopic ultrasonography (EUS) is a modality with high spatial resolution that enables comprehensive observation of the entire pancreas and plays an important role in the diagnosis of pancreatic lesions. Recent advances in diagnostic imaging methods such as ultrasound, computed tomography, and magnetic resonance imaging have increased the incidental detection of pancreatic cystic lesions (PCLs). EUS has been recognized as an essential diagnostic method for the detection and evaluation of PCLs. EUS has two important roles: as a detailed (high-resolution) imaging diagnostic method and as an approach for collecting cyst fluid content by EUS-guided fine needle aspiration for pathological diagnosis or biomarker evaluation. Furthermore, in recent years, the usefulness of contrast-enhanced EUS for the differential diagnosis of PCLs or evaluation of grade of malignancy, and a novel imaging technique called needle-based confocal laser endomicroscopy to observe intraductal structures through a needle, has been reported. An understanding of the morphological characteristics of PCLs depicted by ultrasound imaging and of the benefits and limitations of EUS diagnosis in daily practice is needed.