Computed Tomography Colonoscopy with Faecal Tagging in the Detection of Colorectal Tumours: Report of Local Experience

WH Kwan, WK Chau, WH Yeung, KP Wong, WK Kwok, TM Chan, J Khoo

Hong Kong J Radiol 2004;7:199-205

Objective: To determine the sensitivity and specificity of computed tomography colonoscopy with faecal tagging in the detection of colorectal polyps, adenomas, and carcinomas, with colonoscopy as the reference method.

Patients and Methods: A total of 51 patients underwent computed tomography colonoscopy followed by standard colonoscopy between June 2004 and August 2004. Bowel preparation consisted of 2 L of polyethylene glycol mixed with 25 mL of iopamidol 370 g/L. After colonic air insufflation, patients underwent computed tomography scanning in the supine and prone positions with 1-mm collimation during a single breathhold. Axial and 3-dimensional endoluminal images were interpreted by reporting radiologists. The computed tomography colonoscopic findings were correlated with standard colonoscopic and histological findings.

Results: Computed tomography colonoscopy had a 100% sensitivity for the detection of carcinoma. When direct by-lesion matching was used, the sensitivity of computed tomography colonoscopy for polyp or carcinoma detection was 68% for all lesions. The sensitivity was 59% for detection of polyps of all sizes and 86% for polyps of 5 mm or larger. The sensitivity was 67% for the detection of histologically confirmed adenomas and 85% for polyps of 5 mm or larger. When by-patient matching was used, the sensitivity of computed tomography colonoscopy for polyp or carcinoma detection was 74% for all lesions. The sensitivity for the detection of histologically confirmed adenomas or carcinoma was 81%. The overall specificity for polyp or carcinoma detection was 94%.

Conclusion: Computed tomography colonoscopy is excellent in detecting clinically important colorectal polyps and other tumours.