***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The purpose of this study was to prospect ively compare participant experience and preference of limited preparation computed tomography colonography ( CTC ) with full-preparation colonoscopy in a consecutive series of patients at increased risk of colorectal cancer .  CTC preparation comprised 180 ml diatrizoate meglumine , 80 ml barium and 30 mg bisacodyl . For the colonoscopy preparation 4 l of polyethylene glycol solution was used . Participants ’ experience and preference were compared using the Wilcoxon signed rank test and the chi-squared test , respectively . Associations between preference and experience parameters for the 173 participants were determined by logistic regression .  Diarrhoea occurred in 94 % of participants during CTC preparation . This side effect was perceived as severely or extremely burdensome by 29 % . Nonetheless , the total burden was significantly lower for the CTC preparation than for colonoscopy ( 9 % rated the CTC preparation as severely or extremely burdensome compared with 59 % for colonoscopy ; p < 0.001 ) . Participants experienced significantly more pain , discomfort and total burden with the colonoscopy procedure than with CTC ( p < 0.001 ) . After 5 weeks , 69 % preferred CTC , 8 % were indifferent and 23 % preferred colonoscopy ( p < 0.001 ) . A burdensome colonoscopy preparation and pain at colonoscopy were associated with CTC preference ( p < 0.04 ) . In conclusion , participants ’ experience and preference were rated in favour of CTC with limited bowel preparation compared with full-preparation colonoscopy CONTEXT Conventional colonoscopy is the best available method for detection of colorectal cancer ; however , it is invasive and not without risk . Computed tomographic colonography ( CTC ) , also known as virtual colonoscopy , has been reported to be reasonably accurate in the diagnosis of colorectal neoplasia in studies performed at expert centers . OBJECTIVE To assess the accuracy of CTC in a large number of participants across multiple centers . DESIGN , SETTING , AND PARTICIPANTS A nonr and omized , evaluator-blinded , noninferiority study design of 615 participants aged 50 years or older who were referred for routine , clinical ly indicated colonoscopy in 9 major hospital centers between April 17 , 2000 , and October 3 , 2001 . The CTC was performed by using multislice scanners immediately before st and ard colonoscopy ; findings at colonoscopy were reported before and after segmental unblinding to the CTC results . MAIN OUTCOME MEASURES The sensitivity and specificity of CTC and conventional colonoscopy in detecting participants with lesions sized at least 6 mm . Secondary outcomes included detection of all lesions , detection of advanced lesions , possible technical confounders , participant preferences , and evidence for increasing accuracy with experience . RESULTS A total of 827 lesions were detected in 308 of 600 participants who underwent both procedures ; 104 participants had lesions sized at least 6 mm . The sensitivity of CTC  for detecting participants with 1 or more lesions sized at least 6 mm was 39.0 % ( 95 % confidence interval [ CI ] , 29.6%-48.4 % ) and for lesions sized at least 10 mm , it was 55.0 % ( 95 % CI , 39.9%-70.0 % ) . These results were significantly lower than those for  conventional colonoscopy  , with sensitivities of 99.0 % ( 95 % CI , 97.1%->99.9 % ) and 100 % , respectively . A total of 496 participants were without any lesion sized at least 6 mm . The specificity of CTC and conventional colonoscopy  for detecting participants without any lesion sized at least 6 mm was 90.5 % ( 95 % CI , 87.9%-93.1 % ) and 100 % , respectively , and without lesions sized at least 10 mm , 96.0 % ( 95 % CI , 94.3%-97.6 % ) and 100 % , respectively . Computed tomographic colonography missed 2 of 8 cancers . The accuracy of CTC  varied considerably between centers and did not improve as the study progressed . Participants expressed no clear preference for either technique . CONCLUSIONS Computed tomographic colonography by these methods is not yet ready for widespread clinical application . Techniques and training need to be improved PURPOSE To compare reduced colonic cleansing based on dietary fecal tagging ( FT ) with st and ard ( non-FT ) colonic cleansing with regard to patient acceptance , sensitivity , and specificity . MATERIAL S AND METHODS In 50 patients ( FT group ) , FT was performed by means of diet , magnesium citrate , and a barium suspension . In another 50 patients ( non-FT group ) , preparation was based on polyethylene glycol administration .  All patients underwent conventional colonoscopy after computed tomographic ( CT ) colonography .  Sensitivity and specificity for polyp detection were calculated by using conventional colonography as the reference st and ard . At CT colonography , fecal residue was evaluated . Patients were interviewed to determine discomfort , side effects , sleep quality , final opinion on examination comfort , and whether they would be reluctant to undergo the same examination again . RESULTS FT left more fecal residue but improved differentiation from polyps ( FT specificity , 88 % [ 30 of 34 patients ] ; non-FT , 77 % [ 23 of 30 patients ] ) . Sensitivities were comparable : FT , 88 % ( 14 of 16 patients ) ; non-FT , 85 % ( 17 of 20 patients ) . FT significantly reduced discomfort , side effects , and sleep disturbance , and result ed in an improved final opinion of how comfortable the examination was ( P < .05 ) . Although FT improved patient willingness to repeat the examination , this improvement was not statistically significant ( P > .05 ) . CONCLUSION FT offers the patient a well-tolerated preparation and improves specificity , with improved differentiation of polyps from residual stool BACKGROUND AND AIMS We prospect ively compared the performance of low-dose multidetector computed tomographic colonography ( CTC ) without cathartic preparation with that of colonoscopy for the detection of  colorectal polyps .  METHODS A total of 203 patients underwent low-dose CTC without cathartic preparation followed by colonoscopy . Before CTC , fecal tagging was achieved by adding diatrizoate meglumine and diatrizoate sodium to regular meals . No subtraction of tagged feces was performed . Colonoscopy was performed 3 - 7 days after CTC . Three readers interpreted the CTC examinations separately and independently using a primary 2-dimensional approach using multiplanar reconstructions and 3-dimensional images for further characterization . Colonoscopy with segmental unblinding was used as reference st and ard . The sensitivity of CTC  was calculated both on a per-polyp and a per-patient basis . For the latter , specificity , positive predictive values , and negative predictive values were also calculated . RESULTS CTC had an average sensitivity of 95.5 % ( 95 % confidence interval [ CI ] , 92.1%-99 % ) for the identification of colorectal polyps > or = 8 mm . With regard to per-patient analysis , CTC yielded an average sensitivity of 89.9 % ( 95 % CI , 86%-93.7 % ) , an average specificity of 92.2 % ( 95 % CI , 89.5%-94.9 % ) , an average positive predictive value of 88 % ( 95 % CI , 83.3%-91.5 % ) , and an average negative predictive value of 93.5 % ( 95 % CI , 90.9%-96 % ) . Interobserver agreement was high on a per-polyp basis ( kappa statistic range , .61-.74 ) and high to excellent on a per-patient basis ( kappa statistic range , .79-.91 ) . CONCLUSIONS Low-dose multidetector CTC without cathartic preparation compares favorably with colonoscopy for the detection of colorectal polyps BACKGROUND As part of a multicenter , r and omized controlled trial of the efficacy of flexible sigmoidoscopy for the prevention of bowel cancer , an investigation of the predictors of screening interest was carried out in a sub sample of older adults . METHOD The aim of the study was to establish the predictive power of the Health Belief Model ( HBM ) and to evaluate the contribution of HBM elements in mediating the effect of other demographic and health variables which have been found to be associated with screening interest and participation . A total of 5,099 participants were sent a postal question naire which examined screening interest , attitudes toward screen ing ( benefits and barriers ) , perceived bowel cancer risk , bowel cancer worry , bowel symptoms , health status , state anxiety , and optimism . A total of 3,648 question naires were returned completed , giving a response rate of 71.5 % . RESULTS The results showed that threat , barriers , and benefits explained 47 % of the variance in interest . Demographic and health variables were also associated with screening interest , although most of their effect was mediated by the HBM constructs . DISCUSSION This community study in older adults showed a high level of interest in participating in screening . The large sample size provided the opportunity to test the value of the HBM model and to examine mediation of demographic and health variables . The HBM proved to be a good model of screening interest . These results further our underst and ing of the decision processes in participating in cancer screening and point to directions to increase the level of participation in community sample BACKGROUND Response rates , patient sample characteristics , and patient satisfaction ratings were compared between two surveying methods : ( 1 ) surveys completed at the physician office site ( on-site surveying ) , and ( 2 ) surveys mailed to patient homes following the encounter ( mail-out/mail-back ) . METHODS Surveying was completed at three physician practice s within a 214-physician medical practice . Patients with physician appointments during four-hour time blocks were r and omly split to receive either on-site or mail-based satisfaction surveys . RESULTS Participants younger than 45 years of age provided much higher satisfaction ratings on site than they did by mail ( p < .0001 ) , and participants older than 45 years of age reported satisfaction levels consistently whether on site or by mail . Both age groups reported higher satisfaction with " people aspects " of care on site than they did by mail ( p < .001 ) . DISCUSSION On-site methods may yield satisfaction results that are biased in a positive direction for younger patients and for all patients in which social desirability pressures are prominent . Therefore , organizations that rely on such information may have an inflated view of the patient 's satisfaction with their care delivery experience . Secondly , because the differences in ratings are the greatest for the " people aspects " of care , if improvement efforts are prioritized on the basis of these rapid results , the wrong priorities may be set The purpose was to evaluate low-dose CT colonography without cathartic cleansing in terms of image quality , polyp visualization and patient acceptance .  Sixty-one patients scheduled for colonoscopy  started a  low-fiber diet , lactulose and amidotrizoic-acid for fecal tagging 2 days prior to the CT scan ( st and ard dose , 5.8–8.2 mSv ) . The original raw data of 51 patients were modified and reconstructed at simulated 2.3 and 0.7 mSv levels . Two observers evaluated the st and ard dose scan regarding image quality and polyps . A third evaluated the presence of polyps at all three mSv levels in a blinded prospect i ve way . All observers were blinded to the reference st and ard : colonoscopy . At three times patients were given question naires relating to their experiences and preference . Image quality was sufficient in all patients , but significantly lower in the cecum , sigmoid and rectum . The two observers correctly identified respectively 10/15 ( 67 % ) and 9/15 ( 60 % ) polyps ≥10 mm , with 5 and 8 false-positive lesions ( st and ard dose scan ) . Dose reduction down to 0.7 mSv was not associated with significant changes in diagnostic value ( polyps ≥10 mm ) . Eighty percent of patients preferred CT colonography and 13 % preferred colonoscopy ( P<0.001 ) . CT colonography without cleansing is preferred to colonoscopy and shows sufficient image quality and moderate sensitivity , without impaired diagnostic value at dose-levels as low as 0.7 mSv OBJECTIVES : Visualizing the entire colorectum in screening is an advantage of colonoscopy , and also computed tomographic ( CT ) colonography , another potentially suitable screening test . Our objective was to compare screening CT colonography and colonoscopy in an asymptomatic average-risk population , and to determine whether providing a choice of tests increased participation . METHODS : One thous and and four hundred subjects from the general community , r and omly selected from the parliamentary electoral roll , were allocated one of three screening groups : colonoscopy , CT colonography , or a choice of these tests , and were sent an institutional letter of invitation . Those with symptoms , colorectal cancer in first-degree relatives , or colonoscopy within 5 yr were ineligible . Outcome measures were participation , acceptability of screening , and yield for advanced colorectal neoplasia in participants . RESULTS : Of the subjects , 24.9 % were ineligible ; the overall participation rate was 18.2 % ( 184/1,009 ) . Participation in each screening group was not different . Both tests were accompanied by the same high levels of acceptability ; most participants found colon 
    Output:
    
Studies by radiology authors showed a trend towards stronger preference for CTC  compared with studies by gastroenterology authors .
Symptomatic patients expressed no preference , but screening patients preferred CTC .
There was no difference in preferences between studies using “ masked ” and “ unmasked ” preference ascertainment methods .
There was no evidence of publication bias , while cumulative and exclusion analysis did not show any temporal trend or dominant study .
In conclusion , most included studies reported preference for CTC .
On stratified analysis , screening patients preferred CTC  while diagnostic patients showed no preference .
Studies published in radiology journals showed significantly stronger preference for CTC  compared with studies in gastroenterology or general medicine journals