電子スコープの現状と将来―画像処理の観点から

Electronic Endoscopy and Image Processing of Endoscopic Picture

要旨　電子スコープによる画像は，図形歪がなく，デジタル信号として取り扱える特性を利用して，画像処理を試みた．すなわち“画像の強調”では色の強調，構造（凹凸，立体）の強調をすることにより，実際の症例において，病変の存在診断と質的診断を行ううえで非常に有用であることを示した．また，“画像の計測”においては画像から得られたデジタル信号を数量的に扱うことによって，色の計測，すなわちR，G，Bに分けた数値で表示することにより，異常粘膜と正常粘膜が定量性をもって区別できた．構造（凹凸）の計測においてはステレオ撮影によって得られた像を立体計測および表示ができることを固定標本を用いて，その可能性を示した．このようなコンピューターを利用した画像処理の将来性をも展望した．

　We demonstrated the image processing of endoscopic picture taken by electronic endoscopy, utilizing its following advanteges; digital expression of optical image by charged coupled device (CCD) and endoscopic image of high resolution without any optical bias generated using coherent optical fiber bundle.

　Color and contrast enhanccements were sucessfully done by Ohyama's method. According to it, the color images reduced into R-G-B value by CCD were directly put into computer system (Eclips system, Data General Co. Ltd.), compensating the unlinearities in intensity of R, G and B on a gray scale so as not to destroy the color balance of the original image. By this procedure, indistinct endoscopic findings, such as faint mucosal irregularities in color and unevenness by cancerous invasion, were transformed to the welldemarcated ones, most of which corresponded to the areas of cancer invasion. The results did not differ between in early gastric cancers and in superficial esophageal cancers.

　Image processing also enabled us to analyse the three dimensional difference in mucosal structure quantitatively by measuring the mean color value and analysing stereoscopic picture of a limited area. We also demonstrated the result of application of this procedure to the resected specimen of the stomach.

　In conclusion, the results shown here suggest that the electronic endoscopy provides us the real color image of gastric mucosa with high resolution, which is made possible by independent electric signals or red, green and blue informations. The implication is that the use of computer system will lead to the quantification of endoscopic diagnosis.