10) 微小血管の拡大観察 (4)潰瘍性大腸炎におけるNBI観察の有用性

Magnifying NBI Colonoscopic Findings in Ulcerative Colitis

要旨　narrow band imaging（NBI）内視鏡は波長を狭帯域化した光源で消化管を観察する特殊光内視鏡検査法であり，ヘモグロビン吸収特性の高い狭帯域のNBI内視鏡が臨床応用されている．潰瘍性大腸炎において，通常内視鏡と併用しながらNBI観察を行うと，活動期粘膜では腺口開口部や絨毛状粘膜が明瞭に観察され，緩解期粘膜では血管構築の判定が容易となる．後者において，深部血管が不明瞭な部位では明瞭な部位よりも組織学的に上皮障害や炎症細胞浸潤が高度である．一方，NBI観察と拡大観察を併用すると，活動期粘膜では腺口開口部と絨毛状粘膜が明確に区別できるのに対して，緩解期粘膜の血管は規則的な蜂巣状血管と不規則血管に大別可能となる．潰瘍性大腸炎に合併する腫瘍性病変では大小不同のある不整絨毛状粘膜が観察される．以上のように，拡大NBI観察を行うことにより潰瘍性大腸炎の詳細な病態診断が可能となるので，今後が期待される．

　It is suggested that narrow-band imaging (NBI) colonoscopy can complement conventional colonoscopy for the assessment of severity in ulcerative colitis (UC). In the active mucosa, NBI colonoscopy depicts friability as a black area. In addition, crypt openings and villous structure become evident through the procedure. In the inactive mucosa, there are two types of mucosal vascular pattern (MVP) ; one being composed of deep, green vessels and superficial, black vessels, and the other lacking in superficial vessels. When coupled with a magnifying instrument, the active mucosa can be classified into the mucosa with obvious crypt openings and that with villous structure. MVP in the inactive mucosa is depicted as a honey-comb-like structure or irregular, tortuous structure under magnifying NBI colonoscopy. Furthermore, flat, dysplastic lesions in UC are characterized by tortuous structure under NBI. It is thus suggest that NBI colonoscopy may be a value for the assessment of histologic severity and for cancer surveillance in UC.