CT Colonography Interpretation Guidelines Examined in Study

Recent computed tomography (CT) colonography guidelines recommend that polyps less than 5 mm in size not be reported on CT colonography studies, in consequence of which researchers decided to examine the effect of the guideline by applying the recommendation to an endoscopic database, which collects information about polyps that had been removed and processed.

The guidelines, released by the American College of Radiology's (ACR; Restin, VA, USA), also recommended that patients with one or two polyps, 6 to 9 mm in size and no larger polyps, can have repeat CT colonography in three years rather than prompt polypectomy. The database included information for 10,780 polyps removed from 5,079 patients (among 10,034 colonoscopies) over a five-year interval.

Overall, the study determined that if CT colonography rather than colonoscopy had been used in this population, and assuming 100% sensitivity of CT colonography for polyps larger than 5 mm, then according to post-polypectomy guidelines, 29% of all patients and 30% of patients over age 50 with high-risk adenoma findings would have been interpreted as normal. High-risk adenoma findings were defined according to current post-polypectomy surveillance guidelines as any adenoma 10 mm or larger, any adenoma with high-grade dysplasia or villous elements, or patients with three or more adenomas of any size. An additional 18% of both groups could have had polypectomy delayed for at least three years.

The study was presented at Digestive Disease Week (DDW) 2008, held in San Diego, CA, USA, May 2008. Douglas K. Rex, M.D., chancellor's professor of medicine, Indiana University School of Medicine (Indianapolis, USA) and director of endoscopy at Indiana University Hospital, presented the study's findings and other research during DDW on large sessile adenomas and their association with a high prevalence of synchronous neoplasia.

The study demonstrated that large sessile adenomas are associated with a high prevalence of synchronous neoplasia. Patients with large (20 mm) sessile adenomas who undergo piecemeal endoscopic resection are recommended to have a follow-up examination in three to six months to examine the polypectomy site for residual disease.

The study was a retrospective single academic center review of synchronous neoplastic findings in 190 consecutive patients with intact colons and single large sessile adenomas resected endoscopically. All included patients had at least one full colonoscopy. Synchronous polyps were those removed at the same colonoscopy that discovered the large sessile adenoma, or at any follow-up endoscopic examination within 12 months of discovery of the large sessile adenoma.

Researchers found that 75% of patients had at least one synchronous adenoma, and 190 patients had an average of four synchronous adenomas. Thirty percent of patients had at least one synchronous advanced adenoma (10 mm in size, or with high-grade dysplasia or villous element), and 3% had synchronous lesions with high-grade dysplasia. Synchronous disease was distributed throughout the colon and was likely to be in a distant colonic segment as in the same or an adjacent colonic segment.

The researchers concluded that patients with large sessile adenomas resected endoscopically require follow-up not only to ensure complete resection, but also to ensure clearing of the entire colon.

Related Links:
American College of Radiology
Indiana University School of Medicine