大腸の新しい内視鏡診断―炎症性疾患に対するnarrow band imaging（NBI）

Novel Endoscopic Procedures for the Diagnosis of Colorectal Lesions―Narrow Band Imaging Colonoscopy

要旨　narrow band imaging（NBI）内視鏡は光源の波長をヘモグロビン吸収特性領域に狭帯域化した画像強調内視鏡である．潰瘍性大腸炎におけるNBI観察では，活動期粘膜の腺口開口部や絨毛状粘膜が明瞭となり，緩解期粘膜では血管構築の判定が可能となる．さらに，NBI拡大観察により活動期粘膜では腺口開口部と絨毛状粘膜がより明確に区別され，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できる．一方，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，NBI内視鏡検査を用いることで，潰瘍性大腸炎の病態が血管および腺管構造の点から細分化可能であり，それらの中から腫瘍性病変の拾い上げも可能と思われる．

　We have been applying narrow-band imaging (NBI) colonoscopy for the assessment of severity in patients with ulcerative colitis (UC). In the active mucosa, NBI colonoscopy depicts friability as a black area. In addition, crypt openings and villous structure become evident during 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 an irregular, tortuous structure under magnifying NBI colonoscopy. In our prospective study, a tortuous structure of the mucosa under NBI was highly indicative of dysplastic lesions. Based on these observations, we conclude that NBI magnifying colonoscopy may be of value for the assessment of histologic severity and for cancer surveillance in UC.