大腸の新しい超音波診断―三次元内視鏡的超音波断層法

Three-Dimensional Endoscopic Ultrasonography for Colorectal Region

要旨　大腸領域においても細径超音波プローブによる3D EUSが広く活用されている．直腸領域ではより広い範囲の検索のために直腸肛門用3D硬性超音波プローブが開発されている．ヘリカル走査の情報から表面構築像を含むすべての観測モードにおいてリアルタイム表示が可能になった．表面構築像および複数断層像の3D解析は癌最深部の検索，リンパ節転移診断などに有用と考えられる．完全任意断層面の解析が実現し，有茎性病変の連続した頭茎部の描出により癌の粘膜下層浸潤度レベル診断が可能になった．他分野技術の応用により体内移動する断層面の位置および方向情報を表現できれば，専用機を含むすべてのEUS機器の3D化を期待しうる．

　In endoscopic ultrasonography (EUS) for colorectal region, three-dimensional (3D) EUS using slim ultrasonic probes is being increasingly employed. To observe a much wider area in the anorectal region, a new rectal 3D rigid probe with a 7.5 MHz transducer has been developed.

　In the 3D reconstructions by helical scanning, real-time 3D image reconstructions in all observation modes including the surface-rendering image (SRI) inside a digestive tract are available at examination. 3D processing of SRI and cross-sectional images were valuable for visually exploring the deepest point of cancer invasion and for the diagnosis of lymph node metastases. Arbitrary cross-sectional images of the lesions can be demonstrated in any chosen plane. By examining the image of the junction of the head and the stalk in the pedunculated lesions, the level of submucosal cancer invasion can be evaluated.

　It can be expected that the need to utilize technology used in other fields to acquire data of the variable scanning plane will lead to the development of all EUS equipment that can perform 3D imaging.