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PubMedDate not supplied

Detection of colonic polyps in a phantom model: implications for virtual colonoscopy data acquisition.

PURPOSE: Virtual colonoscopy is a new method of colon examination in which computer-aided 3D visualization of spiral CT simulates fiberoptic colonoscopy. We used a colon phantom containing various-sized spheres to determine the influence of CT acquisition parameters on lesion detectability and sizing. METHOD: Spherical plastic beads with diameters of 2.5, 4, 6, 8 and 10 mm were randomly attached to the inner wall of segments of plastic tubing. Groups of three sealed tubes were scanned at 3/1, 3/2, 5/1 collimation (mm)/pitch settings in orientations perpendicular and parallel to the scanner gantry. For each acquisition, image sets were reconstructed at intervals from 0.5 to 5.0 mm. Two blinded reviewers assessed transverse cross-sections of the phantoms for bead detection, using source CT images for images for acquisitions obtained with the tubes oriented perpendicular to the gantry and using orthogonal reformatted images for scans oriented parallel to the gantry. RESULTS: Detection of beads of > or = 4 mm was 100% for both tube orientations and for all collimator/pitch settings and reconstruction intervals. For the 2.5 mm beads, detection decreased to 78-94% for 5 mm collimation/pitch 2 scans when the phantom sections were oriented parallel to the gantry (p = 0.01). Apparent elongation of beads in the slice direction occurred as the collimation and pitch increased. The majority of the elongation (approximately 75%) was attributable to changing the collimator from 3 to 5 mm, with the remainder of the elongation due to doubling the pitch from 1 to 2. CONCLUSION: CT scanning at 5 mm collimation and up to pitch 2 is adequate for detection of high contrast lesions as small as 4 mm in this model. However, lesion size and geometry are less accurately depicted than at narrower collimation and lower pitch settings.

Colon↗
PubMed1991

Diagnostic accuracy of the double-contrast enema for colonic polyps in patients with or without diverticular disease.

The accuracy of the double-contrast enema for the diagnosis of polypoid lesions in the presence or absence of diverticula was evaluated by retrospectively reviewing the medical records of 202 patients subjected to examination and endoscopy. Analysis of the data on 215 polypoid lesions showed that (a) the diagnostic accuracy of the examination is not affected significantly by the presence of diverticula; (b) the sensitivity of the examination is highly dependent on the size of the polyps (smaller or larger than 0.5 cm) but not on the form (sessile or pedunculated); and (c) the positive predictive value is higher in patients without diverticula. The double-contrast enema was confirmed to be a valid method for the diagnosis of polypoid lesions.

Barium Sulfate↗
PubMed2003

Colon polyp recurrence in a managed care population.

BACKGROUND: Detection, treatment, and subsequent screening of patients with colorectal polyps have considerable implications for public health. Understanding the natural history of colorectal polyps from biologic and health care services standpoints is critical in determining optimal treatment. METHODS: Using computerized data from a large Midwestern health maintenance organization, we identified patients 50 years or older who underwent a polypectomy (index polypectomy) between January 1, 1989, and December 31, 1999. We followed up patients to identify subsequent polypectomies through September 1, 2001. RESULTS: Our final study sample consisted of 8865 individuals with an index polypectomy. Overall, 2704 patients (30.5%) were diagnosed as having recurrent polyps. Kaplan-Meier projections estimate that 50% of patients will have a recurrence within 7.6 years (95% confidence interval [CI], 7.2-8.1 years). Among patients who underwent colon screening at least 9 months after the index polypectomy (52% of original cohort), Kaplan-Meier projections estimate that 50% will have a recurrent polyp within 3.9 years (95% CI, 3.8-4.1 years). CONCLUSIONS: The results demonstrate that, even when screening and treatment are received by those who need it, the risk of colon polyp recurrence is high and many patients do not undergo additional screening. Efforts to increase and monitor ongoing screening of postpolypectomy patients are warranted. In addition, further research is needed to better identify patients at risk for recurrence so that continued screening and other interventions can be targeted at these groups.

Aged↗
PubMed1988

Frequency of isolated proximal colonic polyps among patients referred for colonoscopy.

The American Cancer Society now advocates screening asymptomatic populations over the age of 40 to 50 years for colonic malignancy. It is possible, however, that fecal occult blood testing and sigmoidoscopy to 60 cm would fail to identify patients with adenomatous polyps located only in the proximal colon. The purpose of this study was to determine how many patients without polyps in the distal 60 cm of the colon would have more proximal lesions. Ninety-eight consecutive patients with positive fecal blood test results or suspicious barium enema results were studied, using the assumption that if they had been seen six months earlier, when asymptomatic, they would have been candidates for screening examination. Forty-one (42%) of 98 patients had adenomatous polyps or cancer, and 15 (37%) of these patients had isolated proximal lesions. The polyp detection rate from 0 to 60 cm was significantly less than the detection rate for a full colonoscopy (27% vs 42%). We conclude that isolated proximal colonic polyps may be common.

Adenocarcinoma↗
PubMed1985

Cronkhite-Canada syndrome associated with a rectal cancer and adenomatous changes in colonic polyps.

A 52-year-old man with the clinical features of Cronkhite-Canada syndrome developed rectal cancer. Radiologic and endoscopic examinations revealed gastrointestinal polyposis. Histologic examination of the biopsied polyps showed cystic dilatation of glands with an inflammatory stroma. A later biopsy from a rectal polyp proved to be an adenocarcinoma. The totally resected colon and upper rectum had an ulcerated rectal cancer and numerous polyps; most of the polyps showed histological changes typical of the syndrome. Only three polyps had adenomatous changes at their surfaces. Adenomatous and carcinomatous changes of epithelia can occur in non-neoplastic polyposis of Cronkhite-Canada syndrome from which presumably a carcinoma can develop, as in the present case.

Adenocarcinoma↗
PubMed2004

Prevalence of colonic polyps is not increased in patients with acromegaly: analysis of 60 patients from India.

BACKGROUND: There are conflicting data on the prevalence of colorectal adenomas in patients with acromegaly. It has been suggested that the risk of colorectal adenomas may be dependent on the geographic and ethnic origin of the patients. MATERIALS: Sixty consecutive patients with active acromegaly due to somatotropinoma underwent colonoscopy prior to definitive surgery. They included 35 men and 25 women with a mean (+/- SD) age of 37.4 +/- 13.2 years and a lag time between symptomatology and diagnosis of acromegaly of 64.6 +/- 58.0 months. The control group included 160 patients (88 men, 72 women; mean age, 38.2 +/- 14.0 years) with a diagnosis of irritable bowel syndrome who were also subjected to colonoscopy. None of these patients had previous or family history of colonic neoplasm, bleeding or colonic surgery. RESULTS: Colonoscopic examination was complete to the cecum in 52 patients (88%), and to the splenic flexure in the remaining 12%. In the control group, it was complete to the cecum in 144 patients (90%). Four of the acromegalic patients (6.7%) and five in the control group (3.1%; P=0.24) had hyperplastic polyps. No patient in either of the groups had adenomatous polyps or colonic adenocarcinoma. The group of acromegalic patients with and without polyps did not differ significantly in age, duration of disease, growth hormone levels or glycemic status. The number of skin tags, however, was significantly higher (P=0.04) in the polyp group as compared to those without polyps. CONCLUSION: The present study has failed to demonstrate the high prevalence rate of colonic neoplasia in patients with acromegaly as compared to reports from the Western world.

Acromegaly↗