光学的干渉断層法を用いたダブルバルーン小腸内視鏡検査の有用性

Optical Coherence Tomography at Double-balloon Enteroscopy

要旨　以前は内視鏡観察が困難であった深部小腸が近年のダブルバルーン内視鏡，カプセル内視鏡の開発により観察可能になった．また，光の反射光をイメージングする光学的干渉断層法（optical coherence tomography ; OCT）という新しい診断手法が現在開発中である．OCTは10～20μmの優れた空間分解能を有するため，従来の超音波，CT，MRIで描出不可能であった表層部の微細構造が観察可能である．今回は予備的研究として正常小腸壁のOCT画像と組織学的層構造との対比を小腸の手術摘出標本にピン打ちを行い検討した．また，各種小腸病変におけるOCT画像を提示し，問題点と今後の課題を検討する．

　Optical coherence tomography (OCT) is a new imaging technology that can provide micrometer-scale, cross-sectional images in biological systems. Although analogous to ultrasound B-mode imaging, OCT is superior in spatial resolution (10 to 20μm). On the other hand, the imaging depth of OCT is limited to a few millimeters because light is strongly scattered in most tissue. Yamamoto et al. have recently developed a novel insertion method for enteroscopy, a double-balloon method to improve access to the small intestine for a relatively short time. The present preliminary study shows the OCT image in the deep small intestine during double-balloon enteroscopy. First, OCT image of the submucosal layer of the resected small intestine pierced by a 0.28mm-thick pin was compared to the histologic section. The first high reflective layer corresponded to the mucosal layer, and the next low reflective layer corresponded to the submucosal layer, however, the muscularis mucosae was not detected. Second, we examined comparatively abnormal OCT images in the Meckel's diverticulum and Crohn's ileitis using enteroscopic biopsies. The surface microstructure of lesions coincided well with histologic images. OCT can provide interpretable high-resolution images of surface structures in the small intestine.