拡大電子内視鏡による大腸腫瘍の診断は真に有用か―ビデオを使用した検討

Is High Resolution Magnifying Colonoscope Combined with Indigo Carmine Dye (ICD) Scattering Useful for the Diagnosis of Colorectal Tumors?

要旨　大腸腫瘍の診断について拡大観察が通常観察に比し有用かどうかビデオを使用した方法で検討した．拡大内視鏡使用経験のある内視鏡医6名（初心群：3名，経験群：3名）に，ビデオに編集した20病変の大腸腫瘍（sm₁までの内視鏡治療適応群10例，sm₂以深の内視鏡治療非適応群10例）を各病変について通常観察，インジゴカルミン撒布後の拡大観察の順に見てもらい，診断に関する質問に回答を得た後検討を行った．pit pattern読影可能率（平均）は通常観察15％，拡大観察90％であり，通常観察でもpit pattern読影可能な例が存在した．また拡大観察におけるpit pattern読影可能率および正診率は初心群では各々80％，65％，経験群では98％，81％であり経験群が有意に高かった．腺腫・癌の質的診断については通常観察，拡大観察で差は認められなかった．深達度診断については全20病変の深達度正診率（平均）は通常観察67％，拡大観察86％であり有意に拡大観察の正診率が高かった．pit pattern読影は主観的診断であり，個人差があり，その読み取りには経験が必要であると考えられた．インジゴカルミン撒布後の拡大観察は腺腫・癌の質的診断については，通常観察に比し有用であるとの結論は得られなかったが，深達度診断については通常観察に比し，特に深部浸潤癌で有用であると考えられた．

　We carried out this study to validate the usefulness of magnified observation by comparing the accuracy of its diagnosis for colorectal tumors with that of ordinary observation using video. Twenty lesions (10: adenoma ＆ m or sm₁ cancer, 10: sm cancer deeper than sm₂) were recorded using a high resolution magnifying colonoscope 〔Fujinon EC400 (410) CM or 410CW〕 without ICD (ordinary observation) and with ICD (magnified observation) by video (S-VHS). Six colonoscopists 〔3 beginners (Group A) ＆ 3 experienced (Group B) 〕 reviewed an edited video tape composed of short segments of the 20 randomly-arranged lesions without and with ICD in succession. They were instructed to predict each lesion's histology (adenoma or cancer) and depth of invasion (m, sm₁ or deeper than sm₂) based on the findings by ordinary observation and also by magnified observation (including pit pattern).

　Average detection rate of pit pattern for the lesions was 15％ by ordinary observation, and 90％ by magnified observation. In magnified observation, average detection rate of group A was 80％, and that of group B was 98％ (p＜ 0.01). There was no significant difference regarding diagnostic accuracy of each lesion's histology between two groups. Diagnostic accuracy rate of the depth of invasion is significantly higher by magnified observation combined with ICD than by ordinary observation without ICD especially in colorectal tumors deeper than sm₂.

　Detection of pit pattern depends on the level of endoscopic (magnifying colonoscope) experience. High resolution magnified observation combined with ICD was superior to ordinary observation without ICD in prediction of depth of invasion of colorectal tumors especially of deep invasive cancers.