Bowel Preparation Suitable for Same-day Computed Tomography Colonography and Colonoscopy

Purpose

This study was designed to evaluate whether a bowel preparation used for computed tomography (CT) colonography could also be suitable for same-day colonoscopy regardless of which test was done first.

Method

Six different endoscopists working at 3 separate hospitals evaluated 75 patients who underwent colonoscopy after receiving a bowel preparation that contained contrast material used to tag fecal and fluid material to facilitate CT colonography. This bowel preparation has been used in more than 1500 CT colonography studies. Evaluation included assessment of whether the colon was clean and dry, and whether the contrast material caused any impairment of visualization or clogging of the endoscopes. Some of the patients had first undergone CT colonography followed by same-day colonoscopy, whereas other patients had colonoscopy as their initial test.

Results

Although the contrast material was sometimes perceptible, the volumes were very small, and caused no impairment of mucosal visualization and no clogging of the endoscopes. The bowel preparation was well tolerated. Same-day CT colonography and colonoscopy with fecal tagging was technically possible.

Conclusion

A simple, fairly low cost 1-day bowel preparation with fluid and fecal tagging is suitable for CT colonography and colonoscopy done the same day in either order. However, the preferences of individual endoscopists and difficulties with making oral contrast agents readily available are challenges to widespread adoption of a common bowel preparation regimen.     

Patient acceptance for CT colonography: what is the real issue?

The aim of this study was to evaluate the discomfort associated with CT colonography compared with colonoscopy and bowel purgation cleansing, and to evaluate patient preference between CT colonography and colonoscopy. In a total of 124 patients, scheduled for multidetector virtual CT colonography and diagnostic colonoscopy, patient acceptance and future preference were assessed during the different steps of the procedure (colon preparation, CT examination, and conventional colonoscopy). Patients who described contradictory findings between the degree of discomfort and their preference regarding follow-up examinations were retrospectively reinterviewed regarding the reason for this discrepancy. Colonoscopy was graded slightly more uncomfortable than virtual CT colonography, but the preparation was clearly the most uncomfortable part of the procedure. Concerning their preference regarding follow-up examinations, 71% of the patients preferred virtual CT colonography, 24% preferred colonoscopy, and 5% had no preference. Twenty-eight percent of the patients preferred virtual CT colonography despite that they thought it was equally or even more uncomfortable than colonoscopy. This was mainly due to the faster procedure (17 patients), the lower physical challenge (14 patients), and the lack of sedation (12 patients) of virtual CT colonography. Factors other than the discomfort related to the examinations play an important role in the patient's preference for virtual CT colonography, namely the faster procedure, the lower physical challenge, and the lack of sedation. Since the preparation plays a major decisive factor in the patient acceptance of virtual CT colonography, more attention should be given to fecal tagging.     

Colorectal cancer screening with CT colonography,colonoscopy, and double-contrast barium enema examination: prospective assessment of patient perceptions and preferences

PURPOSE: To prospectively assess and compare perceptions of and preferences for computed tomographic (CT) colonography, colonoscopy, and double-contrast barium enema examination (DCBE) by asymptomatic patients undergoing colorectal cancer screening. MATERIALS AND METHODS: A total of 696 asymptomatic patients at higher-than-average risk undergoing colorectal cancer screening were consecutively recruited to undergo both CT colonography and colonoscopy (group 1), and a like group of 617 patients was separately recruited to undergo both CT colonography and DCBE (group 2). Standard bowel preparations were different between the groups undergoing colonoscopy and DCBE. Each patient completed a questionnaire that assessed preparation inconvenience and discomfort, examination discomfort, willingness to repeat examinations, and examination preference. Survey results were compared for significance by using the Wilcoxon rank sum or chi2 test. RESULTS: The majority of patients considered the preparation to be uncomfortable (group 1, 460 of 515 [89%]; group 2, 482 of 538 [90%]) and inconvenient (group 1, 393 of 502 [78%]; group 2, 427 of 527 [81%]). Reported discomfort was similar at CT colonography and colonoscopy (P =.63) but was less at CT colonography than at DCBE (P <.001). Patients experienced significantly less discomfort than expected at both CT colonography and colonoscopy but not at DCBE. Patients' willingness to undergo frequent rescreening was significantly greater for CT colonography than for either colonoscopy or DCBE. The acceptable time interval between screenings was significantly shorter for all examinations if the bowel preparation could be avoided. Overall, patients preferred CT colonography to colonoscopy (group 1, 72.3% vs 5.1%; P <.001) or to DCBE (group 2, 97.0% vs 0.4%; P <.001). CONCLUSION: Patients undergoing colorectal cancer screening prefer CT colonography to both colonoscopy and DCBE. The majority of patients experience discomfort and inconvenience with cathartic bowel preparation.     

Diagnostic performance of CT colonography for the detection of colorectal polyps.

OBJECTIVE: To investigate the diagnostic value of CT colonography for the detection of colorectal polyps. MATERIALS AND METHODS: From December 2004 to December 2005, 399 patients underwent CT colonography and follow-up conventional colonoscopy. We excluded cases of advanced colorectal cancer. We retrospectively analyzed the CT colonography findings and follow-up conventional colonoscopy findings of 113 patients who had polyps more than 6 mm in diameter. Radiologists using 3D and 2D computer generated displays interpreted the CT colonography images. The colonoscopists were aware of the CT colonography findings before the procedure. RESULTS: CT colonography detected 132 polyps in 107 of the 113 patients and conventional colonoscopy detected 114 colorectal polyps more than 6 mm in diameter in 87 of the 113 patients. The sensitivity of CT colonography analyzed per polyp was 91% (41/45) for polyps more than 10 mm in diameter and 89% (101/114) for polyps more than 6 mm in diameter. Thirteen polyps were missed by CT colonography and were detected on follow-up conventional colonoscopy. CONCLUSION: CT colonography is a sensitive diagnostic tool for the detection of colorectal polyps and adequate bowel preparation, optimal bowel distention and clinical experience are needed to reduce the rate of missing appropriate lesions.     

Effect of different bowel preparations on residual fluid at CT colonography

The effect of different bowel preparations on residual fluid during computed tomographic (CT) colonography was evaluated. Forty-two patients received either a polyethylene glycol electrolyte solution preparation or a phospho-soda preparation the day prior to CT colonography. The amount of residual fluid was calculated for each patient. On average, a phospho-soda preparation provided significantly less residual fluid than a polyethylene glycol electrolyte solution preparation.     

Bowel cleansing methods prior to CT colonography

PURPOSE: To compare the cleansing effect, ease of preparation and side-effects of two cleansing regimens containing either polyethylene glycol solution (PEG) or phospho-soda (Na-P) solution prior to CT colonography in a prospective, randomized, radiologist-blinded design. MATERIAL AND METHODS: Fifty persons were randomized to receive either a PEG preparation or a Na-P preparation prior to CT colonography. On axial 2D images, the rectum, the sigmoid, the descending, the transverse and the cecum/ascending colon were scored semiquantitatively as to cleanness by two radiologists blinded to the bowel preparation regimen. Quality scores in the two groups were compared. Ease of preparation and side-effects were assessed by a questionnaire. RESULTS: The overall quality of the bowel preparation with the Na-P preparation was better than with the PEG preparation with significantly better cleansing scores for the rectum, the sigmoid, the descending and the transverse colon. The Na-P preparation was significantly better tolerated than the PEG preparation with significantly less nausea and significantly less fecal incontinence. CONCLUSION: The quality of the bowel preparation was better with the Na-P preparation than with the PEG preparation prior to CT colonography. Moreover, the Na-P preparation was better tolerated and with fewer side-effects.     

结肠内容物标记法CT结肠成像的研究进展

结肠镜和传统CT结肠成像检查需要严格的导泻或清洁灌肠,多数年老体弱的病人无法耐受。结肠内容物标记法CT结肠成像是通过口服对比剂来标记肠内残留物质,并结合相关后处理技术有效筛查结直肠病变,避免因物理肠道准备给病人带来的不适与痛苦。就结肠内容物标记法CT结肠成像(双能电子净化方法等)的具体标记方法、影像后处理技术、检查性能及临床意义方面的研究予以综述。     

A simplified approach to virtual colonoscopy using different intestinal preparations: preliminary experience with regard to quality, accuracy and patient acceptability

Purpose

The authors assessed the quality, diagnostic accuracy and patient acceptability of computed tomography (CT) colonography performed using a simplified bowel preparation and software for post-processing digital elimination of stool and fluid data from images compared with the examination obtained with conventional preparation.

Materials and methods

Two groups of 40 consecutive asymptomatic patients aged between 48 and 72 years underwent CT colonography. In group A, the CT scan was performed with conventional bowel preparation (a full cathartic dose and oral contrast medium to tag any residue in the 3 days preceding the study). In the second group, CT colonography was performed after a reduced bowel preparation, with the oral contrast medium for residue tagging being administered only on the day of the investigation. Examination quality, diagnostic performance and patient acceptability (rated with a self-completed questionnaire) in the two groups of patients were compared by using the McNemar test.

Results

No significant difference was obtained with regard to examination quality (180 vs. 165 segments free from stools and fluid, p>0.05) and overall diagnostic accuracy (16/17 colonic polyps detected in group A and 12/13 in group B, p>0.05). The questionnaires revealed a greater acceptability of the reduced bowel preparation compared with the standard procedure (p=0.01).

Conclusions

In asymptomatic patients, the use of software for post-processing digital elimination of residue from images in conjunction with reduced bowel preparation does not reduce examination quality or diagnostic performance when compared with the conventional CT colonography technique and is more acceptable to and better tolerated by the patient.     

Role of CT colonography in inflammatory bowel disease

CT colonography (CTC), or virtual colonoscopy, is a non-invasive imaging method that uses CT data sets combined with specialized imaging software to examine the colon. CTC is not used routinely in patients with inflammatory bowel disease (IBD). However, investigating contemporarily the colon, other abdominal organs and the peritoneum with CTC is at times useful in patients with IBD, especially when other diagnostic tools fail. Furthermore, since symptoms of colorectal cancer sometimes superimpose to those of inflammatory disease, it may happen to image patients with IBD incidentally. If clinical signs are suggestive for inflammatory disease, exam technique should be modified accordingly and distinguishing radiological findings searched for.     

Endoluminal CT colonography after an incomplete endoscopic colonoscopy

OBJECTIVE: We evaluated the clinical usefulness of endoluminal CT colonography after an incomplete colonoscopy. SUBJECTS AND METHODS: We prospectively studied 40 patients in whom the cecum could not be reached endoscopically despite adequate bowel preparation. Endoluminal CT colonography (120 kVp, 120 mA, 3-mm collimation, pitch of 2, 1.5-mm interval reconstruction) was performed within 2 hr of incomplete colonoscopy. Two-dimensional multiplanar reformatted images and three-dimensional endoluminal images were analyzed. Twenty-six patients (65%) underwent barium enema immediately after endoluminal CT colonography. We analyzed colonic distention; duration of endoluminal CT colonography; patient tolerance; number of colonic segments seen at colonoscopy, endoluminal CT colonography, and barium enema; and reasons for incomplete colonoscopy as well as colonic and extracolonic findings. RESULTS: Duration of endoluminal CT colonography was 14.2 +/- 4.6 min (mean +/- SD). Endoluminal CT colonography was better tolerated than colonoscopy or barium enema (p < .001). Probable causes for incomplete colonoscopy were identified at endoluminal CT colonography in 74% of 40 patients. Baseline colonic distention in the region of the transverse and right colon was considered adequate before additional air insufflation; however, the addition of air significantly enhanced colonic distention throughout the entire colon (p < .001). Endoluminal CT colonography adequately revealed 96% of all colonic segments; in comparison, barium enema adequately revealed 91% of all segments (p < .05). CONCLUSION: In patients with incomplete colonoscopy, endoluminal CT colonography successfully showed the previously unrevealed colon in more than 90% of patients. Endoluminal CT colonography is a rapid, well-tolerated technique that provides clinically useful colonic and extracolonic information and should be considered for all patients who undergo incomplete colonoscopy.     

Utility of intravenously administered contrast material at CT colonography

PURPOSE: To determine if intravenously administered contrast material improves overall reader confidence in the assessment of the colon, large-bowel wall conspicuity, and diagnostic accuracy in the detection of colorectal polyps and cancers at computed tomographic (CT) colonography. MATERIALS AND METHODS: Two hundred patients underwent CT colonography in both supine and prone positions. A five-point scale was used to assess the effect of contrast enhancement on overall reader confidence and bowel wall conspicuity. Eighty-one patients underwent CT colonography with complete colonoscopic or surgical correlation; diagnostic accuracy was compared in 48 patients who received contrast material and 33 who did not. RESULTS: Bowel preparation was ideal in 38 (19%) of 200 patients. Enhanced prone CT images had significantly better scores for reader confidence (4.9 +/- 0.1 vs 4.6 +/- 0.1, P: <.005) and bowel wall conspicuity (4.6 +/- 0.2 vs 4.2 +/- 0.2, P: <.005) compared with those of nonenhanced prone images despite no significant difference in bowel distention (3.8 +/- 0.2 vs 3.9 +/- 0. 1, P: =.8). Enhancement significantly improved the ability to depict medium (6-9-mm) polyps (75% vs 58%, P: <.05). Three large (10-19-mm) polyps were detected only with contrast enhancement; two remained submerged despite dual positioning. CONCLUSION: The use of intravenously administered contrast material significantly improved reader confidence in the assessment of bowel wall conspicuity and the ability of CT colonography to depict medium polyps in suboptimally prepared colons.     

Recent developments in CT colonography

CT colonography allows reliable, non-invasive, rapid, high resolution imaging of the whole large bowel. Recent advances in technology such as computer-aided detection (CAD), scanning with or without bowel preparation, and low radiation are continually developing to improve the efficacy of this technique. This review will update the reader as to ongoing developments while presenting current thinking from the gastroenterological perspective.     

Diagnostic performance of computed tomography colonography in symptomatic patients and in patients with increased risk for colorectal disease

PURPOSE: To evaluate the diagnostic performance (colorectal lesions) of computed tomography (CT) colonography in 111 patients, a majority of whom were at high risk for colorectal neoplasia. MATERIAL AND METHODS: After bowel preparation, CT colonography was performed, immediately followed by conventional colonoscopy. The diagnostic performance of CT colonography was analyzed relative to lesion size, histological diagnosis, and diagnostic certainty. RESULTS: The sensitivity of CT colonography increased with lesion size (P<0.001), and was 91% (21/23) for lesions > or = 10 mm. All 10 carcinomas and 86% (19/22) of adenomas > or = 5 mm were detected. Unconfirmed or false-positive CT findings were generally small and/or reported with low diagnostic certainty. The specificity of CT colonography would be 45% (30/66; 95% CI 34% to 57%) if patients with findings of any size and any diagnostic certainty were selected for follow-up, and 92% (85/92; 95% CI 85% to 96%) if only patients with CT findings > or = 10 mm classified as certain were selected. CONCLUSION: CT colonography had a high sensitivity for lesions > or = 5 mm. The diagnostic performance increased with lesion size and degree of diagnostic certainty, and was higher for adenomas.     

Screening for colorectal neoplasia with CT colonography: initial experience from the 1st year of coverage by third-party payers

PURPOSE: To evaluate our experience in the 1st year of computed tomographic (CT) colonography screening since the initiation of local third-party payer coverage. MATERIALS AND METHODS: This HIPAA-compliant study was approved by the institutional review board, and informed consent was waived. Over a 1-year period that ended on April 27, 2005, 1110 consecutive adults (585 women, 525 men; mean age, 58.1 years) underwent primary CT colonography screening. More than 99% were covered by managed care agreements. CT colonographic interpretation was performed with primary three-dimensional polyp detection, and the final results were issued within 2 hours. Patients with large (> or =10-mm) polyps were referred for same-day optical colonoscopy, and patients with medium-sized (6-9-mm) lesions had the option of immediate optical colonoscopy or short-term CT colonography surveillance. RESULTS: Large colorectal polyps were identified at CT colonography in 43 (3.9%) of 1110 patients. Medium-sized lesions were identified in 77 (6.9%) patients, 31 (40%) of whom chose optical colonoscopy and 46 (60%) of whom chose CT colonography surveillance. Concordant lesions were identified in 65 of 71 patients who underwent subsequent optical colonoscopy (positive predictive value, 91.5%). Sixty-one (86%) of 71 optical colonoscopic procedures were performed on the same day as CT colonography, thereby avoiding the need for repeat bowel preparation. The actual endoscopic referral rate for positive findings at CT colonography was 6.4% (71 of 1110 patients). The demand for CT colonography screening from primary care physicians and their patients increased throughout the study period. CONCLUSION: As a primary colorectal screening tool, CT colonography covered by third-party payers has an acceptably low endoscopic referral rate and a high concordance of positive findings at optical colonoscopy.     

Colorectal neoplasia screening with CT colonography in average-risk asymptomatic subjects: community-based study

PURPOSE: To evaluate computed tomographic (CT) colonography as a screening tool for average-risk asymptomatic subjects with regard to participation, acceptability, and safety. MATERIALS AND METHODS: CT colonography for colorectal neoplasia screening was offered to 2,000 subjects aged 50-54 and 65-69 years. Only asymptomatic subjects at average risk of colorectal neoplasia were enrolled. Participants underwent CT colonography followed by colonoscopy if CT colonography findings showed any polyps. Acceptability was measured with a 100-point (0, most favorable; 100, least favorable) visual analogue scale (VAS). Chi2 statistic was used to compare participation rates among subgroups. Safety of CT colonography was evaluated by recording all important adverse events. RESULTS: A total of 1,452 subjects were eligible for screening. The adjusted participation rate was 28.4%. Participation was higher in younger subjects and in those from a high socioeconomic region. Major reasons for nonparticipation were insufficient time and perceived good health. Median VAS scores for pain, general satisfaction, embarrassment, and willingness to repeat screening were 13, 6, 8, and 5, respectively. Most subjects found CT colonography better than (60%) or same as (32%) expected. Ninety-three (27.4%) of 340 subjects were referred for colonoscopy, with polyps found in 67 (positive predictive value, 0.73). By adopting criteria that a positive finding at CT colonography is that of a single polyp larger than 5 mm or multiple polyps larger than 2 mm, 14% of CT examinations would have led to colonoscopy; 5.7% of CT findings were false-positive, with no significant impairment in large polyp detection. There were no important adverse events related to CT colonography, although four subjects had syncope or presyncope related to bowel preparation. CONCLUSION: Community-based colorectal neoplasia screening with CT colonography was accompanied by a participation rate that compares favorably with that of similar screening programs. CT colonography was highly acceptable to participants.     

Bowel wall visualisation at CT colonography

Purpose: To evaluate the quality of bowel wall visualisation at CT colonography and the impact of examination in the supine and prone positions.Material and Methods: After bowel preparation, 111 patients underwent CT colonography. Air distension, degree of fluid redistribution with change in body position (supine and prone), influence of residual stool on bowel wall assessability, and quality of overall colon visualisation were evaluated using scales.Results: Thirty of 110 patients (27%) had complete overall visualisation of the colon wall and 52 (47%) had subtotal visualisation of a limited part of the colon. The entire colon was more often air-filled in the prone position (46%) than in the supine position (18%). Joint review of supine and prone data showed that for all colon segments, except the sigmoid (86%), ≥95% of the patients had complete air filling. All patients had residual fluid. In 75% to 99%, depending on segment, fluid did not interfere with the bowel wall visualisation in the combined evaluation of supine and prone data sets. Thirty-one patients had residual stool with potential negative influence on polyp detection.Conclusions: The colon wall was completely, or almost completely, visualised in 75% of the patients, and examination in the supine and prone positions was necessary for complete visualisation.     

CT colonography with minimal bowel preparation: evaluation of tagging quality, patient acceptance and diagnostic accuracy in two iodine-based preparation schemes

Purpose  

The aim of this study was to compare a 1-day with a 2-day iodine bowel preparation for CT colonography in a positive faecal occult blood test (FOBT) screening population.     

Diagnostic accuracy of CT colonography in patients with positive faecal occult blood test: results of the Italian project Legatumori 2003–2006

Purpose

In the framework of the 3-year project of the Italian Legatumori (2003–2006), we evaluated the diagnostic accuracy of computed tomography (CT) colonography in detecting colorectal lesions in a screening population with positive faecal occult blood test (FOBT).

Materials and methods

Two hundred and thirty asymptomatic subjects (age range 45–80 years) were enrolled in the study. CT colonography was performed with standard patient preparation (no faecal tagging) and a 4-detector-row CT scanner. Image analysis was carried out with primary 2D analysis and the use of 3D endoluminal views to solve difficult cases. Patients were referred for conventional colonoscopy in the following situations: detection of three or more suspected lesions with maximum diameter ≤6 mm; evidence of one or more lesions with maximum diameter >6 mm; presence of colonic masses (maximum diameter >3 cm).

Results

CT colonography detected colonic masses in 12 out of 135 subjects (8%). It generated 93 false positives and 19 false negatives in the identification of diminutive lesions (≤6 mm), and 70 false positives and six false negatives in lesions >6 mm. Sensitivity was 83% in smaller lesions and 93% in lesions >6 mm; specificity was 45% and 59%, respectively.

Conclusions

In a screening population with positive FOBT, CT colonography without faecal tagging and no definite size threshold for the reporting of polyps showed very low specificity but high sensitivity in the detection of all colorectal lesions.     

CT colonography practice in the UK: a national survey

AIM: To determine the provision of computed tomography (CT) colonography in UK radiology departments. MATERIALS AND METHODS: A questionnaire relating to the availability of CT colonography, barriers to implementation, clinical indications, technique, and practitioners was posted to clinical directors of UK radiology departments. RESULTS: One hundred and thirty-eight departments responded. Fifty (36%) offered CT colonography in day-to-day clinical practice. Of those that did not, 68 of 87 (64%) cited limited scanner capacity as the main barrier. Of the 50 departments offering a service, 39 (78%) offered CT after incomplete colonoscopy, 36 (72%), after failed barium enema, and 37 (74%) as an alternative to barium enema. Of those offering a service, the number of studies performed varied between one per month (38%) to more than one per day (8%). Total experience varied between 20 or fewer studies (28%) to more than 300 (12%). Full bowel preparation was common (92%), as was dual positioning (90%). Colonography was interpreted by radiologists with a subspecialty interest in gastrointestinal imaging in 64% of centres offering a service. CONCLUSION: CT colonography is widely available in the UK, with approximately one-third of responders offering a service. Experience and throughput varies considerably. Limited CT scanner capacity is the major barrier to further dissemination.     

A retrospective evaluation of patient acceptance of computed tomography colonography ("virtual colonoscopy") in comparison with conventional colonoscopy in an average risk screening population

PURPOSE: To evaluate patient acceptance of computed tomography (CT) colonography compared with conventional colonoscopy by means of a self-assessed questionnaire. MATERIAL AND METHODS: Four-hundred-and-one patients with valid address information from our patient collective were preselected. Patient acceptance was evaluated retrospectively using a self-assessed questionnaire. The patients underwent CT colonography in our institution using 4x or 16x multi-detector row (MDR) CT. Two-hundred-and-forty-six patients returned a completed questionnaire, 157 of these indicating that they had undergone both virtual and conventional colonoscopy. RESULTS: One-hundred-and-twenty (76.4%) of the 157 patients would undergo another CT colonography if necessary, while only 14 patients would not. One-hundred-and-sixteen (73.9%) patients favored the actual examination procedure of CT colonography (P<0.0001), while only 6.4% preferred the conventional method. Preparation prior to CT colonography was experienced as more convenient than preparation prior to conventional colonoscopy (52.2% versus 14%). CONCLUSION: CT colonography was preferred in terms of both preparation and the actual procedure itself.