Present status and future view on virtual endoscopy. Depiction of minute lesions in the large intestine with CT colonography

CT colonography is a new imaging technique using helical CT. We studied the efficacy of CT colonoscopy in the detection of small polyps and depiction of superficial lesions. Concerning the detection of small polyps, we studied 54 patients with abnormality checked by barium enema. Conventional colonoscopy revealed 79 lesions (5 advanced carcinomas, 4 superficial-type adenomas and 70 polyps). CT colonography identified all 5 carcinomas, 3 of the 4 superficial lesions and 43 of the 45 polyps that were 0.5 cm or smaller in diameter, 18 of 22 polyps that were 0.6 to 0.9 cm, and all 3 polyps that were 1.0 cm or more in diameter. There were 92 false positive polyps that were 0.5 cm or smaller in diameter. On a superficial lesion, we could depict a superficial depressive type early colonic carcinoma 1.0 cm in diameter, using very thin-slice CT equipment. In conclusion, CT colonography has a high sensitivity for detection of small polyps and sufficient capability for depiction of superficial lesions. CT colonography may be suitable for screening examinations of the large intestine. (author)