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At least 1,027 records · Page 57Linked to original sources
PubMed1997

Virtual colonoscopy with magnetic resonance imaging: in vitro evaluation of a new concept.

BACKGROUND & AIMS: Screening for colonic polyps is desirable. A new concept based on cross-sectional and endoscopic analysis of a magnetic resonance (MR) data set is presented. METHODS: Ex vivo autopsy colonic specimens, containing artificially placed polyps, were obtained and filled with a gadolinium-containing solution. Forty-four thin-section MR images were obtained in a 1.5-T MR scanner in 28 seconds. A three-dimensional endoscopic fly-through of these images was rendered. Fly-throughs and two-dimensional cross-sectional images were analyzed by two observers for the presence of polyps. RESULTS: The average sensitivity and specificity for the detection of polyps based on three-dimensional endoscopic MR colon imaging were 87% and 96%, respectively. Analysis of cross-sectional images showed an overall sensitivity and specificity of merely 57% and 84%, respectively. The difference in the interpretation of three-dimensional MR colonoscopy and two-dimensional cross-sections was statistically significant (P < 0.001). With three-dimensional MR colonoscopy, overall sensitivity for detection of polyps measuring < or =5 mm in length and diameter was 70%; for larger polyps, it increased to 95% (P < 0.01). CONCLUSIONS: The feasibility of an MR-based endoluminal assessment of the colon is shown. Minimal invasiveness, lack of radiation exposure, and high in vitro diagnostic accuracy warrant further investigation of this novel concept.

Colonic Polyps↗
PubMedDate not supplied

CT colonography: determination of optimal CT technique using a novel colon phantom.

The aim of this study was to determine the thickest slice at the lowest radiation dose for detection of colon polyps larger than 5mm in diameter at computed tomographic (CT) colonography. A colon phantom containing haustral folds, flexures, and straight segments was constructed of borosilicate. One hundred forty simulated polyps (5, 7, 10, and 12 mm) of various shapes (sessile, flat, and pedunculated) were attached at different colon locations (wall, base of fold, on the fold and fold tip). Polyps were positioned parallel, perpendicular, and oblique to the CT gantry. The air-filled phantom was scanned at different slice thicknesses (1.25-5 mm) and x-ray tube currents (5-308 mA). All polyps were identified in all data sets except one (1.25 mm slice thickness, 5 mA). In this acquisition, image noise reduced polyp visibility, and five of 140 (3%) polyps could not be identified. Unidentified polyps were 5 mm, flat or sessile in shape, located on the colon wall or base of the fold, and oblique or parallel to CT gantry. All tested CT techniques provided optimal polyp detection except settings at 1.25 mm and 5 mAs. Thin collimation (<5 mm) scans may not be necessary to detect clinically significant polyps.

Colon↗
PubMedDate not supplied

[Endoscopic treatment of colorectal polyps in a digestive endoscopy outpatient department].

The aim of this report was to evaluate the effectiveness of the endoscopic treatment of colonic polyps to allow secondary prophylaxis in order to prevent the onset of cancer arising from adenomas. From October 2002 to January 2004 we performed 487 colonoscopies on a patient group with the following indications: screening prior to kidney transplant; screening for colorectal cancer (patients positive at faecal occult blood testing); follow-up of patients who had undergone colonic resections for colorectal cancer; patients with other diseases. Colorectal polyps were diagnosed in 15 males and 15 females, with a mean age of 63 years. All the neoplasms were resected during colonoscopy and specimens sent for histological study. The histological examinations yielded the following results: 4 hyperplastic polyps; 9 tubular adenomas (6 with mild, 2 with mild-to-moderate, and 1 with severe dysplasia); 8 tubulo-villous adenomas (3 with mild, 1 with mild-to-moderate, and 4 with moderate dysplasia); 4 villous adenomas (3 with mild and 1 with severe dysplasia); 1 adenocarcinoma; 1 inflammatory polyp; in 3 cases we were unable to retrieve the polyps after polypectomy. Colonoscopic detection of a neoplasm allows us to remove it and send to the pathology laboratory for definitive histological diagnosis. Moreover, snare polypectomy can be a radical treatment for dysplastic polyps without stromal axis and basal membrane infiltration. We therefore conclude that colonoscopy allows not only early diagnosis of colonic neoplasms, but also radical curative treatment in the early stages.

Ambulatory Surgical Procedures↗
PubMed1997

Overexpression of calcium-binding protein calgranulin B in colonic mucosal diseases.

Subtractive two-dimensional gel electrophoresis (2-DE) has been used for the study of the protein patterns of the normal colonic mucosa and the specimens collected from patients diagnosed for inflammatory bowel disease (IBD), colonic polyps and colorectal cancer. We found a 13 kDa protein that was detected in five of seven adenomas and in 13 of 15 colorectal carcinomas while it was absent or only slightly expressed in normal colonic mucosa. Furthermore, this protein occurred in all specimens collected from patients suffering from IBD and its quantity reflected the increased severity of inflammation. The combination of microsequencing and mass spectrometry led to the identification of the 13 kDa spot as calgranulin B. Our results indicate that the production of calgranulin B is unregulated in inflammatory, preneoplastic and neoplastic lesions of colonic mucosa.

Adult↗
PubMed2004

Computed tomographic colonography (CTC): Possibilities and limitations of clinical application in colorectal polyps and cancer.

Colorectal cancer is the second leading cause of cancer-related deaths in Europe and the United States. Most colorectal cancers develop from adenomatous polyps over a number of years. Early detection of polyps eliminates the risk of subsequent carcinomas. Computed tomographic (CT) colonography is a diagnostic technique detecting colorectal neoplasms. With the introduction of multidetector-row computed tomography (MD-CT), CT colonography (CTC) has gained influence as a new diagnostic tool in early detection of colonic pathologies by acquiring volumetric CT data sets of the abdomen. This volumetric data is analyzed using CTC workstations, which provide an interactive display of 2D and 3D images of the colon. In several studies, CTC revealed a high accuracy (sensitivity/patient: 83-100% and specificity/patient: 93-100%) in detecting pathological colonic changes. Furthermore, CTC is an excellent diagnostic technique for the evaluation of patients with incomplete conventional colonoscopy and allows the assessment of extracolonic abdominal and pelvic organs. In this article, the status of CT colonography as a method of detecting colonic polyps and colorectal carcinomas using single- and multidetector-row CT will be reviewed.

Adenomatous Polyposis Coli↗
PubMedDate not supplied

[Practical aspects of intracolonoscopic polypectomy].

Modern views are presented on endoscopic treatment of colonic polyps stressing the superiority of the method over surgical treatment used previously. The factors limiting the possibility of use of the endoscopic method are: the size, the configuration and the number of polyps. However, the extent of these limitations is small. The importance of histological examination of the removed polyp for the tactics of postoperative management is emphasized and a programme is proposed for oncological supervision after coloscopic polypectomy.

Colectomy↗
PubMed1996

Hyperplastic polyposis of the large bowel. Three cases and a review of the literature.

Small hyperplastic polyps of the large bowel constitute a frequent non-neoplastic lesion, whereas large or multiple hyperplastic polyps are rare. Here we report three cases of multiple small polyps together with some large hyperplastic ones. Two of the cases had a primary carcinoma in the bowel before onset of the polyps. The neoplastic potential of the hyperplastic polyp is discussed on the basis of the most recent investigations and the three presented cases. The hyperplastic polyp does not seem to be directly involved in the adenoma-carcinoma sequence, but dysplastic changes can be found in large hyperplastic polyps. In cases of multiple hyperplastic polyps a tendency towards a more uniform distribution of the polyps throughout the large bowel is observed. Hyperplastic colonic polyps may exist as a clinical entity, and a definition based on distribution, multiplicity, size, and symptoms is proposed. Patients with multiple or large hyperplastic polyps should have colonoscopy performed at short intervals, with removal of all lesions larger than 5 mm for histologic examination.

Adenocarcinoma↗
PubMed1993

Laparoscopic-assisted full-thickness endoscopic polypectomy.

PURPOSE: To describe the procedure for endoscopically removing sessile colonic polyps with laparoscopic assistance. METHODS: Technique description and retrospective review of experience. RESULTS: The technique has been used to successfully remove polypoid colonic lesions in three patients. CONCLUSIONS: Laparoscopic-assisted polypectomy allows complete excision of moderate-sized sessile polyps and may spare selected patients a colonic resection.

Animals↗
PubMed1989

Angiomyolipoma of the colon: a new entity in colonic polypoid lesions.

A 67-year-old man with angiomyolipoma on the sigmoid colon is reported. The colonic polyp was pedunculated and diagnosed histologically after endoscopic polypectomy. Angiomyolipoma is one of the benign hamartomas arising principally in the kidneys of patients with or without tuberous sclerosis. Extrarenal angiomyolipoma is rare and this may be the first report of colonic angiomyolipoma.

Aged↗
PubMed1975

CEA levels in patients with colorectal polyps.

Preoperative plasma CEA levels were measured in 93 selected patients with histologically defined colorectal adenomata removed at fibroptic colonoscopy in order to determine whether CEA levels are elevated in patients with colonic polyps, or vary with different histologic patterns. None of the patients had inflammatory bowel disease, previous history of carcinoma, or evidence of liver disease. Fifteen percent of the patients had elevated CEA levels (greater than or equal to 2.5 ng/ml; Hansen method), and two-thirds of these were between 2.5 and 4.0 ng/ml. Increased association of elevated CEA levels was noted with old age, villous adenomas (2- to 4-fold), and increased tumor size (greater than 2.3-cm diameter; 2-fold), but not with foci of dysplasia or carcinoma in situ as such. One-half (7/14) of the patients with elevated CEA levels showed the following: two patients had villous tumors with carcinoma in situ, one had a villous adenoma, two had mixed villous and tubular adenomas (with a high proportion of villous pattern), and two were subsequently shown to have carcinoma elsewhere in the colon. It is uncertain that the polyps were the source of the elevated circulating CEA levels; other factors including smoking and patient selection need to be considered. This preliminary study suggests that patients with colorectal adenomata and elevated circulating CEA may be at higher risk for the development of carcinoma. Further follow-up studies of the malignant potential of the polyp-bearing colon are essential.

Adenoma↗
PubMed1994

beta-Carotene supplementation results in an increased serum and colonic mucosal concentration of beta-carotene and a decrease in alpha-tocopherol concentration in patients with colonic neoplasia.

The aim of this study was to evaluate the colonic mucosal beta-carotene (BC) concentration following supplementation with BC and to determine if an increase in BC concentration influences vitamin E (alpha-tocopherol) status. The concentration of BC and alpha-tocopherol was assessed in serum and colonic tissue obtained from subjects with a history of colonic polyps or resected cancer (Dukes A, B1, or B2). Serum and mucosal biopsy samples were obtained prior to and following 3 months daily p.o. supplementation with 30 mg of BC or placebo. The concentration of BC was significantly increased in serum and colonic mucosa from both polyp and cancer subjects following supplementation as compared to presupplementation values and values from subjects receiving a placebo. The concentration of alpha-tocopherol in serum from cancer subjects was significantly decreased in samples obtained at the end of 3 months of BC supplementation as compared to placebo-matched controls. In BC-supplemented polyp subjects the tissue concentration of alpha-tocopherol was also significantly decreased relative to presupplementation values. The results indicate that BC supplementation does result in a significant accumulation of BC in the colonic mucosa but that the alpha-tocopherol concentration in both serum and colonic tissue may be compromised by an increased intake of BC. The mechanism for the decrease in alpha-tocopherol in conjunction with the increase in BC will require further study in order to develop strategies which will prevent vitamin E deficiency in BC-supplemented individuals.

Adult↗
PubMed2006

The use of 3D surface fitting for robust polyp detection and classification in CT colonography.

In this paper we describe the development of a computationally efficient computer-aided detection (CAD) algorithm based on the evaluation of the surface morphology that is employed for the detection of colonic polyps in computed tomography (CT) colonography. Initial polyp candidate voxels were detected using the surface normal intersection values. These candidate voxels were clustered using the normal direction, convexity test, region growing and Gaussian distribution. The local colonic surface was classified as polyp or fold using a feature normalized nearest neighborhood classifier. The main merit of this paper is the methodology applied to select the robust features derived from the colon surface that have a high discriminative power for polyp/fold classification. The devised polyp detection scheme entails a low computational overhead (typically takes 2.20min per dataset) and shows 100% sensitivity for phantom polyps greater than 5mm. It also shows 100% sensitivity for real polyps larger than 10mm and 91.67% sensitivity for polyps between 5 to 10mm with an average of 4.5 false positives per dataset. The experimental data indicates that the proposed CAD polyp detection scheme outperforms other techniques that identify the polyps using features that sample the colon surface curvature especially when applied to low-dose datasets.

Algorithms↗
PubMed1975

Definitive treatment of "malignant" polyps of the colon.

There has been an unremitting rise in incidence of colonic cancer in this country with no recent improvement in cure rate. As a result the evolution of colorectal cancer has been the focus of considerable attention with an enlarging body of evidence pointing to the common neoplastic polyp as a precursor to malignancy. "Neoplastic" polyps include "adenomatous polyps," "villous adenomas" and, lately recognized, "villo-glandular polyps." Experience with endoscopic removal of over 2,000 colonic polyps (with no mortality) has introduced two questions of prime concern to the surgeon: (1) What constitutes clinical malignancy in a polyp? AND, (2) When should laparatomy supplant or follow endoscopic removal? Eight hundred and ninety-two consecutive adenomatous (tubular), villous, villoglandular (villo-tubular) and "polypoid cancer" polyps are analyzed, 855 of which have been followed for 6 months to 4 years. Support is offered to the concept that villous and tubular growth patterns are merely variants of a similar base disturbance in cell renewal. Superficial cancer (carcinoma-in-situ) occurred in 6.6% of neoplastic polyps and represents no threat if the polyp is completely removed. Only when the cancer penetrates the muscularis mucosae should it be regarded as "invasive." The term "malignant polyp" should be reserved for this form. Invasive cancer was found in 5.0% of neoplastic polyps in this series. Only in this group need the question of further surgical intervention be raised. Major considerations influencing a decision for subsequent laparotomy are polyp size and gross morphology (i.e. sessile or pedunculated), histologic type (of the polyp and of the cancer itself), adequacy of clearance between depth of invasion and plane of polyp resection, and the patient's age and general condition. These are analyzed. Twenty-five of 46 patients with "malignant polyps" were subjected to abdominal exploration: 17 showed no residual cancer, whereas 8 (5 with recognized incomplete endoscopic removal) had tumor in the bowel wall. Of the remaining 21 patients, for whom endoscopic polypectomy alone was deemed appropriate, none have shown residual or recurrent cancer on clinical and endoscopic followup. Colonoscopy appears to be a most promising approach in terms of the goals of cancer programs, offering both prophylaxis and opportunity for treatment at a favorable stage of disease.

Adenoma↗
PubMedDate not supplied

Power, sample size and smallest detectable effect determination for multivariate studies.

This paper discusses some general methods for determining approximate power, sample size, and smallest detectable effect for studies of multiple risk factors. These methods are based on standard large-sample formulae for determining the power of chi-square tests, and emphasis is given to determinations for Pearson chi 2 tests in multiway contingency tables. The methods are illustrated in application to the design of a clinical trial of the preventive effect of alpha-tocopherol, ascorbic acid and beta-carotene on colon polyp recurrence, and a case-control study of the joint effect of smoking and asbestos exposure on lung cancer incidence.

Biometry↗
PubMed1988

Colonic lymphoid follicles associated with colonic neoplasms.

In 3,399 patients more than 40 years of age undergoing air-contrast enema examinations a prospective evaluation was done for the presence of colonic lymphoid follicles. In 3,315 patients there was no evidence of lymphoid follicles. Colonic neoplasms were diagnosed in 8.47% of these individuals. Eighty-four patients were found to have radiographically identifiable follicles. Fifty-eight of these 84 patients (69%) with lymphoid follicles had a synchronous (n = 19) or previous (n = 14) colonic neoplasm or a synchronous (n = 24) or previous (n = 1) colonic polyp. There were no consistent clinical or radiographic features that distinguished the patients with and without a neoplastic association. However, 90% of men with lymphoid follicles had associated neoplasms, whereas only 58% of women did. Because of the frequent association, detection of colonic lymphoid follicles in patients in this age group should lead to a vigorous search for subtle colonic neoplasms that may not be apparent because of technical limitations of the study.

Adult↗
PubMed2000

Virtual endoscopy--comparison with colonoscopy in the detection of space-occupying lesions of the colon.

BACKGROUND AND STUDY AIMS: A new technique has been described which combines abdominal helical computed tomography (CT) scanning and virtual reality computer technology, known as virtual colonoscopy (VC); the reconstructed images provide a simulation of the interior of the colon as viewed by endoscopy. We compared VC with conventional colonoscopy in patients with suspected or known colonic neoplasia. PATIENTS AND METHODS: A total of 38 patients, in whom there was a high likelihood of colonic polyps or cancer, underwent a noncontrast helical CT scan of the abdomen and pelvis after regular colonoscopy bowel preparation. The images were reconstructed into a VC presentation and compared with the subsequent conventional colonoscopy in a blinded manner. RESULTS: Conventional colonoscopy identified a total of 24 polyps 5 mm or greater. VC correctly identified five of 13 polyps 5-9 mm in size, and ten of 11 lesions greater than or equal to 10 mm in diameter. The reasons for four missed lesions were identified as being secondary to a collapsed rectum in two patients and stool in the right colon in two patients. The sensitivity and specificity per patient of VC for lesions greater than or equal to 5 mm were 66.7% and 75.0% respectively, and for lesions greater than 1 cm were 90.0% and 82.1%, respectively. CONCLUSIONS: Virtual colonoscopy is feasible, well tolerated, and capable of detecting most lesions greater than 10 mm in diameter. This technique is continuing to be developed and warrants further evaluation as a diagnostic and screening tool in colorectal neoplasia.

Adult↗
PubMed1986

Vertebral osteomyelitis caused by Streptococcus bovis.

The association of Streptococcus bovis septicemia with abnominal neoplasms has been well-documented. The case of a man who presented with vertebral osteomyelitis due to S. bovis is reported; he was subsequently found to have bacteremia and colonic polyps. It is recommended that patients who present with localized as well as generalized S. bovis infections undergo yearly colonoscopy.

Aged↗