5）画像強調・拡大観察―NBI

Clinical Usefulness of NBI（Narrow Band Imaging）Magnification for Diagnosis of Colorectal Tumors

要旨　NBI（narrow band imaging）拡大観察は，粘膜表層の微小血管構築の詳細な観察を可能にした．大腸腫瘍性病変に対するNBI拡大観察の臨床的意義は，まず病変拾い上げ診断に対する有用性であるが，肯定・否定両報告が複数あり，一定のコンセンサスが得られていない．一方，腫瘍・非腫瘍の鑑別診断における有用性は世界的にコンセンサスが得られている．また，色素を用いず整～軽度不整pit様構造（II，III，IV型，V_I軽度不整）を間接的に診断できるというメリットは診療の簡便化に有用である．微小血管構築とpit様構造を総合的に評価することで，早期大腸癌の深達度診断が可能である．しかし，早期癌の深達度診断に用いるNBI拡大観察所見分類が乱立しており，全国的な統一が必要である．

　We reviewed the clinical usefulness of NBI（narrow band imaging）endoscopy in its improvement of detection of colorectal neoplasia, differential diagnosis between neoplasia and non-neoplasia, pit pattern diagnosis and invasion depth diagnosis of carcinoma in colorectal neoplasia. NBI is commonly considered to be useful in differential diagnosis between neoplasia and non-neoplasia & pit pattern diagnosis for regular pits without chromoendoscopy. NBI magnification is expected to be useful in qualitative diagnosis of colorectal carcinoma through assessment of both microvessel structure and pit like pattern on the lesion surface（NBI Hiroshima Classification）. Also, we introduced several NBI magnification classifications for colorectal tumor in Japan. Furthermore, we proposed a new non-magnification NBI classification for colorectal tumor（CTNIG Classification）.