大腸癌の診断に注腸X線検査は必要か―原則不要とする立場から：注腸X線検査の早期大腸癌に対する存在診断能と深達度診断能（内視鏡的治療の適応病変を中心に）

Studies on Evaluating the Accuracy of Radiological Examinations in the Detection and Diagnosis of the Depth of Invasion of Early Colorectal Cancer

要旨　注腸X線検査の早期大腸癌に対する存在診断能，深達度診断能を検討した．(1)X線検査が先行し，次いで全大腸内視鏡検査が施行された322病変〔Ⅰ型：247(m＋sm₁236，sm₂＋sm₃11)，Ⅱ型：75(m＋sm₁65，sm₂＋sm₃10)〕に対するX線の存在診断能は，Ⅰ型91％，Ⅱa66％，Ⅱa＋Ⅱc，Ⅱc，Ⅱc＋Ⅱa29％であった．一方，表面型234病変の精密X線の描出能は85％で，Ⅱa82％，Ⅱa＋Ⅱc98％，Ⅱc，Ⅱc＋Ⅱa79％であった．ルーチン検査では描出能は低く，表面型大腸癌のスクリーニング法としては不十分である．(2)X線と内視鏡・細径超音波プローブ併用例での深達度診断能は90～92％と同等であり，内視鏡で存在診断，深達度診断された後の精密X線の意義について見直しの時期に来ていると考えられる．今後，早期大腸癌の存在診断能向上のためには内視鏡診断の積極的な導入とスクリーニングX線の改良が課題と思われる．

　This study was carried out to evaluate the accuracy of radiological examinations in the detection and diagnosis of the depth of invasion of early colorectal cancer. (1) Three hundred and twenty-two lesions that were examed by radiological screening first followed by total colonoscopy were analyzed. The diagnostic accuracy of radiological screening for protruding lesions, superficial elevated lesions, and superficial depressed lesions was 91%, 66%, and 29%, resepectively, indicating the difficulty of detecting lesions by radiological screening. On the other hand, visualization of superficial elevated lesions, superficial elevated-and-depressed lesions, and superficial depressed lesions by close radiological examination was possible in 82%, 98%, and 79%, respectively. (2) The diagnostic accuracy using close radiological examination, total colonoscopy, and ultrasound using a microscanner was 92%, 90%, and 90%, respectively. Therefore, it was suggested that reassessment should be made of the need to perform close radiological examination for lesions detected by endoscopy. To obtain a better detection rate for early colorectal cancer, wider use of endoscopy in screening and improvement of radiological screening are necessary.