Role of CT Virtual Colonoscopy in Diagnosis of Colo-Rectal Neoplasms

Abstract

Purpose: to assess the role of CT colonography (virtual colonoscopy) as a non-invasive imaging technique in detection and diagnosis of colorectal neoplasia using conventional colonoscopy and/or operative findings as a reference standard, as well as highlighting its advantages and possible pitfalls. Methods: sixty patients were examined by CT after standard bowel preparation, rectal insufflation and IV contrast injection. Imaging was performed in both supine and prone positions. Evaluation consisted of review of the transverse CT images, sagittal and coronal reformations and 3D endoluminal lmages. CT colonographic findings were correlated with standard conventional colonoscopic and/or operative findings. Results: Virtual colonoscopy correctly identified all 6 carcinomas (100%), 12 out of the 13 polyps that measured 10mm or more (92.3%), 19 of the 23 polyps that measured 6 - 9 mm (82.6%) and 28 out of 48 polyps that measured 5mm or less (58.3%). There were 11 false positive findings of polyps by virtual colonoscopy and no false positive findings of cancer. Virtual colonoscopy also detected 35 incidental extracolonic findings in 25 patients while non were detected by conventional colonoscopy. 17 of the 24 patients who had no lesions during conventional colonoscopy were considered free of lesions by CT colonography yielding a per-patient specificity of 70.8% Conclusion: CT colonography has high sensitivity for the detection of clinically important polyps and cancer as well as multiple advantages over conventional colonoscopy in imaging of colorectal neoplasms