Overview of computed tomographic colonography
- Stephan Anderson, MD
Stephan Anderson, MD
- Associate Professor of Radiology
- Boston University School of Medicine
- Section Editors
- Kenneth K Tanabe, MD
Kenneth K Tanabe, MD
- Section Editor — Gastrointestinal Malignancies
- Professor of Surgery
- Harvard Medical School
- Jonathan B Kruskal, MD, PhD
Jonathan B Kruskal, MD, PhD
- Section Editor — Kidney Disease
- Professor of Radiology
- Harvard Medical School
Computed tomographic (CT) colonography (also virtual colonoscopy or CT colography) provides a computer-simulated endoluminal perspective of the air-filled distended colon . The technique uses conventional spiral or helical CT scan images acquired as an uninterrupted volume of data and employs sophisticated post-processing software to generate images that allow the operator to evaluate a cleansed colon in any chosen direction.
This topic will review the preparation, technique, and risks of CT colonography. The effectiveness of CT colonography in screening and the diagnosis of colorectal cancer are discussed in detail, separately. (See "Clinical presentation, diagnosis, and staging of colorectal cancer", section on 'CT colonography' and "Tests for screening for colorectal cancer: Stool tests, radiologic imaging and endoscopy", section on 'Computed tomography colonography'.)
Indications — Potential indications for CT colonography include the following:
●Screening for colorectal cancer (CRC) – CT colonography is an option for CRC screening in asymptomatic average-risk individuals over the age of 50 years [2,3]. However, the role of CT colonography in screening for CRC is controversial. While there is consensus that CT colonography should not be used for screening in patients at increased risk for CRC (eg, history of adenomas, inflammatory bowel disease, familial CRC syndrome), guidelines differ in their recommendations for CT colonography in average-risk individuals. Guidelines for CRC screening are discussed in detail, separately. (See "Screening for colorectal cancer: Strategies in patients at average risk", section on 'Guidelines for average-risk screening'.)
●Evaluation for synchronous CRC – In patients with a CRC in whom a complete colonoscopy cannot be performed due to the inability to pass the colonoscope beyond an obstructing tumor, a CT colography can rule out a proximal synchronous CRC. (See "Screening for colorectal cancer: Strategies in patients at average risk", section on 'Guidelines for average-risk screening'.)
- Levine MS, Yee J. History, evolution, and current status of radiologic imaging tests for colorectal cancer screening. Radiology 2014; 273:S160.
- Levin B, Lieberman DA, McFarland B, et al. Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. Gastroenterology 2008; 134:1570.
- U.S. Preventive Services Task Force. Screening for colorectal cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2008; 149:627.
- Chang KJ, Rekhi SS Jr, Anderson SW, Soto JA. Fluid tagging for CT colonography: effectiveness of a 2-hour iodinated oral preparation after incomplete optical colonoscopy. J Comput Assist Tomogr 2011; 35:91.
- Kim B, Park SH, Hong GS, et al. Iohexol versus diatrizoate for fecal/fluid tagging during CT colonography performed with cathartic preparation: comparison of examination quality. Eur Radiol 2015; 25:1561.
- Iannaccone R, Laghi A, Catalano C, et al. Computed tomographic colonography without cathartic preparation for the detection of colorectal polyps. Gastroenterology 2004; 127:1300.
- Callstrom MR, Johnson CD, Fletcher JG, et al. CT colonography without cathartic preparation: feasibility study. Radiology 2001; 219:693.
- Zalis ME, Hahn PF. Digital subtraction bowel cleansing in CT colonography. AJR Am J Roentgenol 2001; 176:646.
- Lefere PA, Gryspeerdt SS, Dewyspelaere J, et al. Dietary fecal tagging as a cleansing method before CT colonography: initial results polyp detection and patient acceptance. Radiology 2002; 224:393.
- Thomeer M, Carbone I, Bosmans H, et al. Stool tagging applied in thin-slice multidetector computed tomography colonography. J Comput Assist Tomogr 2003; 27:132.
- Zalis ME, Perumpillichira J, Del Frate C, Hahn PF. CT colonography: digital subtraction bowel cleansing with mucosal reconstruction initial observations. Radiology 2003; 226:911.
- Bielen D, Thomeer M, Vanbeckevoort D, et al. Dry preparation for virtual CT colonography with fecal tagging using water-soluble contrast medium: initial results. Eur Radiol 2003; 13:453.
- Chen D, Liang Z, Wax MR, et al. A novel approach to extract colon lumen from CT images for virtual colonoscopy. IEEE Trans Med Imaging 2000; 19:1220.
- Stoop EM, de Haan MC, de Wijkerslooth TR, et al. Participation and yield of colonoscopy versus non-cathartic CT colonography in population-based screening for colorectal cancer: a randomised controlled trial. Lancet Oncol 2012; 13:55.
- Summers RM, Yao J, Pickhardt PJ, et al. Computed tomographic virtual colonoscopy computer-aided polyp detection in a screening population. Gastroenterology 2005; 129:1832.
- Halligan S, Altman DG, Mallett S, et al. Computed tomographic colonography: assessment of radiologist performance with and without computer-aided detection. Gastroenterology 2006; 131:1690.
- Trilisky I, Wroblewski K, Vannier MW, et al. CT colonography with computer-aided detection: recognizing the causes of false-positive reader results. Radiographics 2014; 34:1885.
- Sosna J, Blachar A, Amitai M, et al. Colonic perforation at CT colonography: assessment of risk in a multicenter large cohort. Radiology 2006; 239:457.
- 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.
- Pickhardt PJ. Incidence of colonic perforation at CT colonography: review of existing data and implications for screening of asymptomatic adults. Radiology 2006; 239:313.
- Pendsé DA, Taylor SA. Complications of CT colonography: a review. Eur J Radiol 2013; 82:1159.
- Berrington de González A, Kim KP, Knudsen AB, et al. Radiation-related cancer risks from CT colonography screening: a risk-benefit analysis. AJR Am J Roentgenol 2011; 196:816.
- Boellaard TN, Venema HW, Streekstra GJ, Stoker J. Effective radiation dose in CT colonography: is there a downward trend? Acad Radiol 2012; 19:1127.
- Chang KJ, Caovan DB, Grand DJ, et al. Reducing radiation dose at CT colonography: decreasing tube voltage to 100 kVp. Radiology 2013; 266:791.
- Yamamura S, Oda S, Imuta M, et al. Reducing the Radiation Dose for CT Colonography: Effect of Low Tube Voltage and Iterative Reconstruction. Acad Radiol 2016; 23:155.
- Shen H, Liang D, Luo M, et al. Pilot study on image quality and radiation dose of CT colonography with adaptive iterative dose reduction three-dimensional. PLoS One 2015; 10:e0117116.
- Ginnerup Pedersen B, Rosenkilde M, Christiansen TE, Laurberg S. Extracolonic findings at computed tomography colonography are a challenge. Gut 2003; 52:1744.
- Pickhardt PJ, Hanson ME. Incidental adnexal masses detected at low-dose unenhanced CT in asymptomatic women age 50 and older: implications for clinical management and ovarian cancer screening. Radiology 2010; 257:144.
- Macari M, Nevsky G, Bonavita J, et al. CT colonography in senior versus nonsenior patients: extracolonic findings, recommendations for additional imaging, and polyp prevalence. Radiology 2011; 259:767.
- Kim YS, Kim N, Kim SY, et al. Extracolonic findings in an asymptomatic screening population undergoing intravenous contrast-enhanced computed tomography colonography. J Gastroenterol Hepatol 2008; 23:e49.
- Flicker MS, Tsoukas AT, Hazra A, Dachman AH. Economic impact of extracolonic findings at computed tomographic colonography. J Comput Assist Tomogr 2008; 32:497.
- Gluecker TM, Johnson CD, Wilson LA, et al. Extracolonic findings at CT colonography: evaluation of prevalence and cost in a screening population. Gastroenterology 2003; 124:911.
- Pickhardt PJ, Kim DH, Meiners RJ, et al. Colorectal and extracolonic cancers detected at screening CT colonography in 10,286 asymptomatic adults. Radiology 2010; 255:83.
- PATIENT SELECTION
- PATIENT PREPARATION
- Technique and data acquisition
- Image processing and reconstruction
- TEST PERFORMANCE
- Complications related to preparation
- Colonic perforation
- Radiation exposure
- Incidental extracolonic findings
- Other complications
- QUALITY INDICATORS
- INFORMATION FOR PATIENTS
- SUMMARY AND RECOMMENDATIONS