Computed tomographic colonography for colorectal screening

Computed tomographic colonography (CTC) is a specialized computed tomographic examination that has been optimized for the detection of colorectal polyps. The technology has undergone major advances in recent years and there is emerging consensus that state-of-the-art CTC results in performance characteristics comparable to those of optical colonoscopy for polyps ≥ 8 mm in size. Effective polyp detection rests on the quality of several components of the examination, which must all be optimized in order to maintain appropriate sensitivity and specificity, including adequate bowel preparation, good colonic distension, sufficient scanning parameters, and appropriate interpretation. The emergence of CTC provides another method of colonic evaluation for colorectal cancer screening and prevention. In contrast to a mutually exclusive approach to screening, the availability of both optical colonoscopy and CTC should hopefully improve overall compliance rates for colorectal screening. The ultimate role of this technique in the screening program continues to evolve. There is currently considerable variability in the materials and methods used in CTC. This article describes the approach used at the University of Wisconsin, which has been validated in a large multicenter screening trial and which is currently used for an active CTC-based colorectal cancer screening program.

References

• 1 Seeff L C, Manninen D L, Dong F B. et al . Is there endoscopic capacity to provide colorectal cancer screening to the unscreened population in the United States?.  Gastroenterology. 2004;  127 1661-1677
• 2 Pickhardt P J, Choi J R, Hwang I. et al . Computed tomographic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults.  N Engl J Med. 2003;  349 2191-2200
• 3 Hofstad B, Vatn M H, Andersen S N. et al . Growth of colorectal polyps: redetection and evaluation of unresected polyps for a period of three years.  Gut. 1996;  39 449-456
• 4 Gondal G, Grotmol T, Hofstad B. et al . The Norwegian Colorectal Cancer Prevention (NORCCAP) screening study: baseline findings and implementations for clinical work-up in age groups 50 - 64 years.  Scand J Gastroenterol. 2003;  38 635-642
• 5 Kim D H, Pickhardt P J, Taylor A J. Characteristics of advanced adenomas detected at CT colonography screening: implications for appropriate polyp size thresholds for polypectomy versus surveillance.  AJR Am J Roentgenol;. 2007;  188 1-7
• 6 Odom S R, Duffy S D, Barone J E. et al . The rate of adenocarcinoma in endoscopically removed colorectal polyps.  Am Surg. 2005;  71 1024-1026
• 7 Vijan S, Hwang I, Inadomi J. et al . The cost-effectiveness of CT colonography in screening for colorectal neoplasia.  Am J Gastroenterol. 2006 Dec 11;  (Epub ahead of print)
• 8 Pickhardt P J, Lee A D, McFarland E G, Taylor A J. Linear polyp measurement at CT colonography: in vitro and in vivo comparison of two-dimensional and three-dimensional displays.  Radiology. 2005;  236 872-878
• 9 Brenner D J, Georgsson M A. Mass screening with CT colonography: should radiation exposure be of concern.  Gastroenterology. 2005;  129 328-337
• 10 Chin M, Mendelson R, Edwards J. et al . Computed tomographic colonography: prevalence, nature, and clinical significance of extracolonic findings in a community screening program.  Am J Gastrenterol. 2005;  100 2771-2776
• 11 Pickhardt P J, Taylor A J, Kim D H. et al . Screening for colorectal neoplasia with CT colonography: initial experience from the first year of coverage by third-party payers.  Radiology. 2006;  241 417-425
• 12 Shinners T J, Pickhardt P J, Taylor A J. et al . Patient-controlled room air insufflation versus automated carbon dioxide delivery for CT colonography.  AJR Am J Roentgenol. 2006;  186 1491-1496
• 13 Taylor S A, Halligan S, Goh V. et al . Optimizing colonic distention for multi-detector row CT colonography: effect of hyoscine butylbromide and rectal balloon catheter.  Radiology. 2003;  229 99-108
• 14 Bruzzi J F, Moss A C, Brennan D D. et al . Efficacy of IV Buscopan as a muscle relaxant in CT colonography.  Eur Radiol. 2003;  13 2264-2270
• 15 Rogalla P, Lembcke A, Ruckert J C. et al . Spasmolysis at CT colonography: Butyl scopolamine versus glucagon.  Radiology. 2005;  236 184-188
• 16 Johnson C D, Harmsen W S, Wilson L A. et al . Prospective blinded evaluation of computed tomographic colonography for screen detection of colorectal polyps.  Gastroenterology. 2003;  125 311-319
• 17 Rockey D C, Paulsen E K, Niedzwiecki D. et al . Analysis of air contrast barium enema, computed tomographic colonography, and colonoscopy: prospective comparison.  Lancet. 2005;  365 305-311
• 18 Cotton P B, Durkalski V L, Pineau B C. et al . Computed tomographic colonography (virtual colonoscopy): a multicenter comparison with standard colonoscopy for detection of colorectal neoplasia.  JAMA. 2004;  291 1713-1719
• 19 Pickhardt P J, Nugent P A, Choi J R, Schindler W R. Flat colorectal lesions in asymptomatic adults: implications for screening with CT virtual colonoscopy.  AJR Am J Roentgenol. 2004;  183 1343-1347
• 20 Pickhardt P J. The incidence of colonic perforation at CT colonography: review of the existing data and the implications for screening of asymptomatic adults.  Radiology. 2006;  239 313-316
• 21 Burling D, Halligan S, Slater A. et al . Potentially serious adverse events at CT colonography in symptomatic patients: national survey of the United Kingdom.  Radiology. 2006;  239 464-471
• 22 Markowitz G S, Stokes M B, Radhakrishnan J, D’Agati V D. Acute phosphate nephropathy following oral sodium phosphate bowel purgative: an underrecognized cause of chronic renal failure.  J Am Soc Nephrol. 2005;  16 3389-3396