適応型帯域強調処理による大腸腫瘍の画像解析―表面型大腸腫瘍を中心とした腺口形態と陥凹面の検討

Pit Pattern Diagnosis of Colorectal Tumors by Adaptive Band-enhancement

要旨　大腸粘膜の微細構造を通常内視鏡観察時に，より詳細に観察する目的で，画質向上ユニット（EVIP-230）を用いて，大腸腫瘍284例（隆起型224例，表面型60例）に対し通常観察，輪郭強調処理および帯域強調処理を行い，各条件下における腺口形態の識別の可否を検討した．更に陥凹面を有する表面型大腸腫瘍56例について，陥凹面の解析をその形態と陥凹係数により検討した．帯域強調処理はいずれの条件下でも高い腺口識別率を示した．陥凹面が棘状のものでは100％，星芒状では96.9％が腺腫であり，面状では93.3％が早期癌であった．腺腫の陥凹係数は0.17±0.1，早期癌は0.48±0.2であり，両者間には統計学上有意差が認められた．帯域強調処理による腺口形態の識別は大腸腫瘍において有用であり，その診断能の向上のためには陥凹面の形態と陥凹係数に注目することが重要であると考えられた．

　We employed an image processor (EVIP-230, Olympus) to improve the recognition of pit patterns of colorectal tumors. To reveal the usefulness of adaptive band-enhancement, we compared pit pattern identification-rate when using ordinary observation, edgeenhancement and band-enhacement in 284 cases of colorectal tumors including 224 protruded lesions and 60 superficial ones. Additionaly, we investigated the relation between the characteristics of depression and histological diagnosis in 56 cases of superficial lesions with depression.

　As a result, band-enhancement was shown to be superior to other types of observation in recognizing pit patterns of colorectal tumors, especially for superficaltype lesions. Further improvement in differential diagnosis was able to be achieved by classifying the patterns and measuring the proportion of depression. When the shape of the depression was spicular or asteroid, histological diagnosis was adenoma. In contrast, when it was round to ovoid, histological diagnosis was early cancer in 93.3%. The proportion of depression to the whole lesion (depression index) was 0.17 ± 0.1 in adenomas and 0.48 ± 0.2 in early cancers. Significant difference was observed between the two groups.