Computed tomography colonography in 2014: An update on technique and indications

Twenty years after its introduction,computed tomographic colonography(CTC)has reached its maturity,and it can reasonably be considered the best radiological diagnostic test for imaging colorectal cancer(CRC)and polyps.This examination technique is less invasive than colonoscopy(CS),easy to perform,and standardized.Reduced bowel preparation and colonic distention using carbon dioxide favor patient compliance.Widespread implementation of a new image reconstruction algorithm has minimized radiation exposure,and the use of dedicated software with enhanced views has enabled easier image interpretation.Integration in the routine workflow of a computer-aided detection algorithm reduces perceptual errors,particularly for small polyps.Consolidated evidence from the literature shows that the diagnostic performances for the detection of CRC and large polyps in symptomatic and asymptomatic individuals are similar to CS and are largely superior to barium enema,the latter of which should be strongly discouraged.Favorable data regarding CTC performance open the possibility for many different indications,some of which are already supported by evidence-based data:incomplete,failed,or unfeasible CS;symptomatic,elderly,and frail patients;and investigation of diverticular disease.Other indications are still being debated and,thus,are recommended only if CS is unfeasible:the use of CTC in CRC screening and in surveillance after surgery for CRC or polypectomy.In order for CTC to be used appropriately,contraindications such as acute abdominal conditions(diverticulitis or the acute phase of inflammatory bowel diseases)and surveillance in patients with a long-standing history of ulcerative colitis or Crohn’s disease and in those with hereditary colonic syndromes should not be overlooked.This will maximize the benefits of the technique and minimize potential sources of frustration or disappointment for both referring clinicians and patients.     

Extracolonic Findings at Virtual Colonoscopy: An Important Consideration in Asymptomatic Colorectal Cancer Screening

Background  Virtual colonoscopy has been evaluated for use as a colorectal cancer screening tool, and in prior studies, it has been estimated that the evaluation of extra-colonic findings adds $28-$34 per patient studied. Methods  As an ancillary study to a prospective cohort study comparing virtual colonoscopy to conventional colonoscopy for colorectal cancer detection, the investigators retrospectively determined the number and estimated costs of all clinic visits, imaging and laboratory studies, and medical procedures that were generated as a direct result of extra-colonic findings at virtual colonoscopy. Results  We enrolled 143 subjects who underwent CTC followed by conventional colonoscopy. Data were available for 136 subjects, and 134 (98%) had at least one extra-colonic finding on CT. Evaluation of extra-colonic findings was performed in 32 subjects (24%). These subjects underwent 73 imaging studies, 30 laboratory studies, 44 clinic visits, 6 medical procedures, and 44 new or return outpatient visits over a mean of 38 months following the CTC. The most common findings causing further evaluation were lung nodules and indeterminate kidney lesions. No extra-colonic malignancies were found in this study. A total of $33,690 was spent in evaluating extra-colonic findings, which is $248 per patient enrolled. Conclusions  The cost of the evaluation of extra-colonic findings following virtual colonoscopy may be much higher in actual practice than is suggested by prior studies. This will impact the cost-effectiveness of using virtual colonoscopy for asymptomatic colorectal cancer screening and underscores the importance of standardizing the reporting of extra-colonic findings to encourage appropriate follow-up. Presented at the American College of Gastroenterology Annual Meeting, October 2006.     

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

In the United States, colorectal cancer (CRC) is the third most common cancer diagnosed among men and women and the second leading cause of death from cancer. CRC largely can be prevented by the detection and removal of adenomatous polyps, and survival is significantly better when CRC is diagnosed while still localized. In 2006 to 2007, the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology came together to develop consensus guidelines for the detection of adenomatous polyps and CRC in asymptomatic average-risk adults. In this update of each organization's guidelines, screening tests are grouped into those that primarily detect cancer early and those that can detect cancer early and also can detect adenomatous polyps, thus providing a greater potential for prevention through polypectomy. When possible, clinicians should make patients aware of the full range of screening options, but at a minimum they should be prepared to offer patients a choice between a screening test that primarily is effective at early cancer detection and a screening test that is effective at both early cancer detection and cancer prevention through the detection and removal of polyps. It is the strong opinion of these 3 organizations that colon cancer prevention should be the primary goal of screening.