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Colon cancer is the second most common cause of cancer death and the first one in non-smoking persons. None of the current colorectal caner screening options is ideal. As for mammography in breast cancer screening, virtual colonoscopy, although still in clinical evaluation, promises to become a primary screening method as it is performant, quick, non-invasive and cheaper than conventional colonoscopy.
OBJECTIVE: To show our experience and results in Virtual Colonoscopy (VC). MATERIAL AND METHOD: Five hundred patients with personal or familial history of colorectal carcinoma and/or adenomas, or any kind of coloproctologic symptoms were studied. VCs were practiced using a helical CT scanner (300 patients) and a multislice CT scanner (200 patients) a few hours after Conventional Colonoscopy (CC), considered the gold standard. The patients were evaluated in a prospective blind study, to determine sensitivity and specificity of VC. Findings were classified as: 1) normal studies; 2) studies with pathological findings. This one was subdivided into: 2a) Lesions below 5 mm., 2b) Lesions between 5-9 mm., 2c) Lesions above 9 mm. RESULTS: VC detected 253 normal studies whereas CC only detected 233. The sensitivity and specificity for each subgroup were: 2a) 87.8% and 86.9%; 2b) 95.6% and 91.4%; 2c) 100.0% and 100.0% respectively. CONCLUSION: VC is a feasible and useful method for evaluating the entire colon. It is well tolerated, it has no complications and a high sensitivity and specificity for elevated lesions, especially the ones above or equal to 5 mm.
The authors present their own initial experience with virtual colonoscopy. Both benign and malignant stenosing processes of the colon and rectum, which make examining oral parts of the colon using colonoscopy or irrigography impossible, are the main indication for the procedure described. The authors' first experience with this method is totally positive. The more experienced the examiners, the better interpretation of the findings not only by radiologists but also by operating surgeons. In certain indications, the examination has its firm place in the algorithm of the facultative examinations prior to the colorectal carcinoma surgical procedures.
Virtual colonoscopy (VC) is a minimally invasive tool that utilizes modern CT technology for colorectal evaluation. Since its inception in 1994, VC has continued to rapidly evolve and improve as a diagnostic screening tool. Early success using primary two-dimensional (2D) detection in polyp-rich cohorts was followed by disappointing results in low prevalence populations. Subsequent introduction of the three-dimensional (3D) endoluminal display for primary polyp detection and oral contrast tagging has transformed VC into an effective primary screening tool. This state-of-the-art VC technique has already proven to be a viable enterprise when combined with existing optical colonoscopy practice. More widespread implementation of VC screening faces multiple challenges, but these are all greatly overshadowed by the immediate need for increased participation in effective colorectal screening. Given its relatively noninvasive nature and the wide availability of CT, VC holds significant potential for addressing a very important yet preventable public health concern. This review will cover current VC technique, compare the existing multi-center VC trials, discuss issues related to primary VC screening, and briefly update the progress of our VC screening program.
This paper presents a centerline-based parametric model of colon for collision detection and visualization of the colon lumen for colonoscopy simulator. The prevailing marching cubes algorithm for 3D surface construction can provide a high resolution mesh of triangular elements of the colon lumen from CT data. But a well organized mesh structure reflecting the geometric information of the colon is essential to fast and accurate computation of contact between the colonoscope and colon, and the corresponding reflective force in the colonoscopy simulator. The colon is modeled as parametric arrangement of triangular elements with its surface along the centerline of the colon. All the vertices are parameterized according to the radial angle along the centerline, so that the triangles around the viewpoint can be found fast. The centerline-based parametric colon model has 75,744 triangular elements compared to 373,364 of the model constructed by the marching cubes algorithm.
Double contrast barium enema and colonoscopy are great value in the diagnosis of lesions of the colon, especially polyps. This study involved 73 patients. The results were in agreement in 71,2% of cases and disagreed in 23,3%. In 5,5%, colonoscopy was technically inadequate. Classical barium enema remains indicated for the detection of carcinoma or in elderly or bedridden individuals. By contrast, barium enema should be replaced by double contrast study in the aetiological evaluation of rectal bleeding. In our own series, the diagnosis was positive in 92% of cases as long as both the radiological and endoscopic techniques were used.
Total colonoscopy was performed in 3,740 cases within approximately 4 years. Results show, that total colonoscopy may be used as a primary method of clinical examination in an optimal way, if the technically improved, new class of instruments is used. The new short ACMI F6S is especially suited for this approach, yielding reliable results in about 92% of all patients, if the colon is clean and if there are no organic stenoses present.
Colonoscopy is seldom performed in a small community hospital, due to the high cost of instruments and other factors but the author has accomplished 450 colonoscopies in that setting, with a small complication rate and no mortality.
Colonoscopy, as an established endoscopic procedure in adults, is thought to be of great value in children and juveniles as well. The main indications for its use are intestinal hemorrhage, polypectomy, diarrhoea of uncertain origin, uncertain x-ray findings as well as the confirmation of a diagnosis made by biopsy. The choice of instruments used, preparations prior to the examination and premedication are dependent upon the child's age. 32 children, aged between 1--14 years, and 41 juveniles between 15 and 18 years were examined. Most common diagnoses were Crohn's disease (29), polyps (7) and ulcerative colitis (4). Others were unspecific colitis (3), follicular hyperplasia of the terminal ileum (2), lymphangiectasia (2), one hemangioma and one rectal ulcer. In 24 patients endoscopy revealed nothing pathological within the colon. Examinations should be performed only by skilled endoscopists with special experience of the problems of colonoscopy in children.
Fiberoptic colonscopy is a useful adjunct to the barium enema in establishing the nature of colonic narrowing for which surgical intervention is being considered in patients who are not clinically obstructed. When the mucosa can be demonstrated to be free of disease, celiotomy and resection can be avoided. Even without significant narrowing, it is sometimes possible to limit the extent of resection by proving the process to be benign. On review of 500 consecutive colonscopic procedures, "colonic narrowing" was the indication or finding in 47 patients. Barium enema had been inconclusive in 34 of these, whereas colonoscopy was inconclusive in only seven. In 34 patients the decision concerning surgical amangement was influenced by colonoscopy, and the accuracy of the endoscopic findings in the majority was confirmed by biopsy, laparoscopy, or celiotomy. On the basis of radiographic and endoscopic studies, 29 patients were not explored and in none was there delay or failure in the diagnosis of malignancy. There were no complications or deaths. Three illustrative cases are presented with correlative endoscopic and radiographic material.
Seventy-nine blood cultures were obtained from 15 patients undergoing diagnostic colonoscopy. Aerobic and anaerobic culture technics showed no evidence of bacteremia during or after the procedure. The colonoscope was passed to the cecum in 12 of the 15 patients. The time of the procedure varied from 15-60 minutes with an average of 30 minutes. The results of this study supplies further evidence that bacteremia during colonoscopy is an infrequent occurrence.
Colonoscopy is a valuable diagnostic and therapeutic tool. In the present series, 12 polyps, a villous adenoma, and three new cases of ulcerative colitis were found in symptomatic patients with negative barium enemas. Surgical intervention was avoided in two patients suspected of having carcinoma. This study proves the safety and the value of colonoscopy to the community hospital surgeon. It also affords a better means of evaluating the patient with inflammatory disease, and avoids the genetic effects of repeated x-rays.
A case of interstitial emphysema involving the mesentery and serosa of the sigmoid colon after volvulus reduced by colonoscopy is presented. The case is reported as a form of pneumatosis intestinalis although it does not conform to the classical clinicopathologic picture of pneumatosis cystoides intestinalis. The infrequent occurrence of this condition in association with volvulus and/or colonoscopy is discussed.
During the examination of the colon by fibre-optic colonoscopy in 200 consecutive patients it was possible to reach the caecum or suspected lesion in 80% of cases. Careful bowel preparation, sedation and detailed attention to techniques described are necessary for safe and successful performance of this procedure. In 85% of examinations, colonoscopy produced positive results including the definition of uncertain radiological lesions in 45 patients, finding of a cause for rectal bleeding not shown on barium studies in 15 patients, the assessment of inflammatory bowel disease in 28 patients, and the removal of polyps in 40 patients. Important was the finding of a normal colon in 49 cases, which obviated unnecessary surgery. Colonic perforation occurred in 2 patients. The limitations and complications of the procedure must be realised, but it is concluded that the colonoscope provides a valuable and effective means of diagnosis and therapy of lesions in the large bowel.
Massive rectal bleeding can pose a difficult problem in management. We describe a new technique employing peroperative colonic irrigation and direct colonoscopy to identify the source of the bleeding, so avoiding blind colonic resection.
We describe a new technique of operative orthograde colonic washout followed by colonoscopy for use in patients with severe colonic haemorrhage. We report its use in four patients in whom the exact source of bleeding was localized and treated. In two of these cases a policy of 'blind' hemicolectomy would have been incorrect. The technique is simple and safe, and we advocate its use during laparotomy for major colonic haemorrhage.
A patient who sustained a colonic perforation during therapeutic colonoscopy was treated successfully by laparoscopic repair. Laparoscopy was performed 5 h after polypectomy. Fecal matter was not identified in the peritoneal cavity. Local peritonitis was mild. The laceration was oversewn with five sutures using the extracorporeal endoscopic knot technique. The appendix epiploica was then anchored over the lesion. The postoperative recovery was rapid and uneventful. Laparoscopic surgery may become a useful tool for the safe, effective, and minimally invasive management of iatrogenic colonic perforation.
For quality control purposes, a computer based auditing system for colonoscopy has been developed in the Department of Colorectal Surgery, Singapore General Hospital, Singapore. The first year's experience was reviewed to determine both workload patterns and the individual operators' performances. Colonoscopic completion rates, both as raw data and cusum transformations, were used as indices of quality control. The mean colonoscopic completion rate for the Unit was 97.0% and, when temporal trends were analysed by cusum, all operators consistently met or exceeded the minimum target completion rate of 90%.