Early Experience of Virtual Colonoscopy on Colorectal Cancer

ABSTRACT

PURPOSE: Virtual colonoscopy (VC) is a newly developing non-invasive technique used to detect polyps and cancers of the colon. The aim of this study is to assess the efficacy of VC in the detection of synchronous polyps or cancers in preoperative patients as well as metachronous polyps of postoperative colorectal cancer patients. METHODS: Both VC and conventional colonoscopy (CFS) were performed on 40 patients with colorectal cancer (10 cases of preoperative state and 30 cases of postoperative follow-up) during Sep. 2002 to June 2003 in Daegu Catholic Medical Centre, Catholic University of Daegu, Republic of Korea. The success rate and the detection rate of polyps or cancers along with the locations and sizes of masses and the findings of anastomotic site were compared between VC and CFS. RESULTS: The entire colon was clearly visualized by CFS in all cases. In the preoperative group, VC was successfully performed in 8 out of 10 cases (80%). 8 out of 10 cancers, 4 out of 4 polyps (5 mm or more in diameter) and 3 out of 6 polyps (5 mm or less in diameter) were identified. The success rate of VC in the postoperative group were 58% of low anterior resection (LAR) from cecum to hepatic flexure, 89% of LAR, 45% of right hemicolectomy (RHC) from hepatic flexure to splenic flexure, 63% of LAR, 45% of RHC from splenic flexure to sigmoid colon, and 53% of LAR, 72% of RHC in rectum. The causes of failure were inadequate bowel distension and retained fluid. In postoperative group, VC identified only 3 of 7 polyps(5 mm or more in diameter), 1 of 10 polyps (5 mm or less in diameter) and 1 of 1 recurrent cancer. The anastomotic site was clearly seen by VC in 9 of 19 cases (47%) of LAR and 3 of 11 cases (27%) of RHC. VC also identified 28 extracolonic findings. CONCLUSIONS: Although the efficacy of VC in postoperative colorectal cancer follow up seems to be disappointing, but it can be used as an alternative method for patients with incomplete conventional colonoscopy due to anastomotic site stricture or for other failed cases. Further technological advancement of VC is needed in order for it to replace conventional colonoscopy as a postoperative follow-up test.