超音波内視鏡診断―今後の展開

Endoscopic Ultrasonography―Future Prospects

要旨　1980年の超音波内視鏡（endoscopic ultrasonography；EUS）の開発以来，その臨床応用，進歩には目を見張るものがあり，胆膵疾患のみならず消化管疾患への適応の拡大がなされてきた．超音波内視鏡の今後の展開として考えられるのは，三次元超音波内視鏡（3D-EUS），超音波内視鏡下穿刺術（EUS-FNA），電子ラジアル超音波内視鏡，集束超音波などが考えられる．まず現在の3D-EUSは，本質的に超音波プローブであるため十分なpenetrationが得られず，ストロークも短いため大きな病変が対象とならない．やはり，通常型EUSによる三次元超音波内視鏡の開発が望まれる．次にEUS-FNAは，本邦においても汎用されるようになったが，今後進むべき方向は，膵仮性嚢胞ドレナージ，腹腔神経叢ブロックのみならず，遺伝子治療，樹状細胞等による免疫療法などのEUS-FNIと思われるが，局注する薬剤，ウイルスベクター，アンチセンス等の基礎的研究の進歩を待たざるを得ないのが現状である．電子ラジアル式EUSは，超音波造影剤の進歩と相まって今後汎用されると思われる．また集束超音波は，膵癌等の低侵襲的治療の可能性を秘めており，今後の発展が期待される．

　Endoscopic ultrasonography (EUS) was developed in 1980 and has widened its usefulness not only for billiopancreatic diseases but also for gastrointestinal diseases. For clinical examination, EUS has become an indispensable imaging tool. Concerning the prospects of EUS, three-dimensional EUS, EUS-guided FNA, electro radial scanning EUS, focused ultrasound therapy etc. should be considered. 3D-EUS, which is commercially available, is basically an ultrasonic thin probe, but it dosen't have enough penetration or scanning stroke length. Because of this,3D-EUS by means of conventional EUS is expected to be developed. Recently EUS-guided FNA has become popular in Japan. Furthermore EUS-guided fine needle therapy such as pseudocyst drainage, celiac plexus neurolysis, gene therapy, immunotherapy with dendrocyto etc. has begun to be used in clinical fields. However, at present, endosonographers have to wait for the basic development of new agents, virus vector and antisense without adverse effects. While sonographic enhancement agents are being developed, electro radial scanning EUS is becoming popular. In addition, focused ultrasound therapy has, in the near future, the potential to treat pancreatic cancer with less invasiveness.

　1) Deparment of Gastroenterology, Kitasato Univesity East Hospital, Sagamihara, Japan