5．消化管壁の組織像と超音波像との比較

Comparison of Histological Picture and Ultrasonographic Picture of the Alimentary Tract Wall

要旨　消化管壁の組織像と超音波内視鏡像との対比は，癌の深達度診断に不可欠であり，超音波内視鏡が開発された当初から繰り返し検討されてきた．1984年に相部により消化管壁の5層構造が初めて報告され，消化管内腔より第1層と第2層が粘膜層，第3層が粘膜下層，第4層が固有筋層，第5層が漿膜下層および漿膜であるとした．この5層構造は現在も基本的な所見として広く用いられている．その後，高周波数の機器が開発され，解像度が極めて良好になったため相次いで新たな層構造の解釈や粘膜筋板の描出について報告された．それにより壁は9層，11層，13層などに観察されるとされる．これらの検討により深達度診断の精度が向上すると考えられる．

　The comparison of a histological picture and a ultrasonographic picture of the alimentary tract wall was essential for a diagnosis of the depth of invasion, and it has been evaluated repeatedly since the development of endoscopic ultrasonography. In 1984, Aibe originally reported a five-layer structure of the alimentary tract: the first and second layers were regarded as the mucosal layer, the third layer was as the submucosal layer, the fourth layer was as the proper muscle, and the fifth layer was as the subserosal layer and the serosa. This five-layer structure has been widely used as a fundamental finding. Recently, a higher frequency ultrasonographic machine with higher resolution would enable us to find some more detailed layer structures and the muscular layer of mucosa. The development of new technology demonstrates that the alimentary tract wall would be observed as a nine-layer structure, an elevenlayer structure or a thirteen-layer structure. These investigations would make more precise diagnosis of the depth of invasion.