CT colonography through 128 slice MDCT provides a virtual noninvasive opportunity to visualize the Colon with very good resolution at minimum radiation, in multiple planes in both retrograde and anterograde directions through 3D reconstruction software, hence lumen missed by VC behind the haustral folds can be visualized in the anterograde direction. We in the present study evaluated the ability of virtual colonoscopy to detect colorectal cancers and polyps in suspected patients of colonic pathology Methods: This prospective study was conducted in the Department of Radiology, Prahtima Institute of Medical Sciences, Naganoor, Karimnagar. Patients aged 30 to 80 yrs. complaining of colonic symptoms like constipation, melena, haematochezia, loss of weight and known cases of colonic pathology. All the patients will be given 30 ml heptulac (lactulose) mixed in water at 9 pm the earlier day and put them on NBM overnight which will be followed by rectal enema twice spaced 4 hours and 1 hour before the CT scan. Virtual colonoscopy (CT-VC) examinations will be performed according to a standard protocol. Results: n=32 cases with suspected colonic pathologies n=21 cases had colonic findings forming 65% of the cases with positive colonic findings 48% had some kind of polyps while 29% had carcinoma colon. N=6 cases had carcinoma of the colon among the N=32 cases forming 18.7% of the cases. While 67% percent of the carcinomas were in the distal colon 33% had carcinoma of the proximal colon. Among the 6 cases of carcinoma colon, n=4 cases had advancing carcinoma beyond the colonic wall. Among the n=4 cases 50 percent n=2 cases presented with metastasis to distal organs. Conclusions: Virtual colonoscopy was found to be very useful because of 3D viewing of colon both in forward as well as reverse directions. However, it has limitations because it depends on proper bowel preparation. Electronic bowel cleansing or barium fecal tagging may improve sensitivity. This technique is very useful in elderly patients where sedation is contraindicated and also useful in patients with Diverticulosis where chances of perforation are high by conventional colonoscopy.

Keywords: Virtual Colonoscopy, Colonic Pathologies.

1. EJ Kuipers, Willam MG, David L, Thomas S, et al. Colorectal Cancer. Nat Rev Dis Primers 2015; 1: 15065.
2. ICMR Subcommittee on Colorectal Cancer. CONSENSUS DOCUMENT FOR MANAGEMENT OF COLORECTAL CANCER. available online. https://www.icmr.nic.in/sites/default/files/guidelines/Colorectal%20Cancer_0.pdf [Accessed on 12/12/2019]

3. Muto T, Bussey HJ, Morson BC. The evolution of cancer of the colon and rectum. Cancer 1975; 36:2251-2270.
4. Winawer SJ, Zauber AG, Ho MN, et al. Prevention of colorectal cancer by colonoscopic polypectomy. The National Polyp Study Workgroup. N Engl J Med 1993; 329:1977-1981.
5. Muller AD, Sonnenberg A. Prevention of colorectal cancer by flexible endoscopy and polypectomy. A case-control study of 32,702 veterans. Ann Intern Med 1995; 123:904-910.
6. Thiis-Evensen E, Hoff GS, Sauar J, Langmark F, Majak BM, Vatn MH. Population-based surveillance by colonoscopy: effect on the incidence of colorectal cancer. Telemark Polyp Study I. Scand J Gastroenterol 1999; 34:414-420.
7. Citarda F, Tomaselli G, Capocaccia R, Barcherini S, Crespi M. Efficacy in standard clinical practice of colonoscopic polypectomy in reducing colorectal cancer incidence. Gut 2001; 48:812-815.
8. Abhishek Bhandari, Melissa Woodhouse, Samir Gupta. Colorectal cancer is a leading cause of cancer incidence and mortality among adults younger than 50 years in the USA: a SEER-based analysis with comparison to other young-onset cancers. J Investig Med 2017; 65(2):311-15.
9. Kim YS, Kim N, Kim SH, et al. The efficacy of intravenous contrast-enhanced 16-raw multidetector CT colonography for detecting patients with colorectal polyps in an asymptomatic population in Korea. J Clin Gastroenterol 2008; 42(7): 791 – 798.
10. Ozsunar Y, Coskun G, Delibaș N, Uz B, Yükselen V. Diagnostic accuracy and tolerability of contrast-enhanced CT colonoscopy in symptomatic patients with increased risk for colorectal cancer. Eur J Radiol 2009; 71 ( 3 ): 513 – 518.
11. Perry J. Pickhardt, MD and David H. Kim. CT Colonography. Pitfalls in
    Radiol Clin North Am. 2013; 51(1): 69–88.
12. Macari M, Bini EJ, Jacobs SL, Lange N, Lui YW. Filling defects at CT colonography. Radio Graphics 2003;23:1073–91.
13. Thomas Mang, Andrea Maier, Christina Plank, Christina Mueller-Mang,
    Christian Herold, Wolfgang Schima. Pitfalls in Multi-Detector Row CT Colonography. RadioGraphics 2007; 27:431–454.
14. Summers RM, Yao J, Pickhardt PJ, et al. Computed Tomographic virtual colonoscopy computer-aided polyp detection in a screening population. Gastroenterology 2005;129:1832–1844.
15. Yoshida H, Nappi J, Mac Eneaney P, Rubin DT, Dachman AH. Computer-aided diagnosis scheme for detection of polyps at CT colonography. Radio Graphics 2002;22:963–979.
16. Taylor SA, Halligan S, Burling D, et al. Computer-assisted reader software versus expert reviewers for polyp detection on CT colonography. AJR Am J Roentgenol 2006;186:696–702.
17. Summers RM, Jerebko AK, Franaszek M, Malley JD, Johnson CD. Colonic polyps: complementary role of computer-aided detection in CT colonography. Radiology 2002;225:391–399.

Dr P Ramravi Kumar

Associate Professor, Department of Radiology, Prathima Institute of Medical Sciences, Naganoor, Karimnagar