Image quality and patient acceptance of four regimens with different amounts of mild laxatives for CT colonography. AJR Am J Roentgenol. 2008;191:158-167. [PMID: 18562740 DOI: 10.2214/ajr.07.3128]

Comparison of Diatrizoate and Iohexol for Patient Acceptance and Fecal-Tagging Performance in Noncathartic CT Colonography

OBJECTIVE

The aim of this study was to compare diatrizoate and iohexol regarding patient acceptance and fecal-tagging performance in noncathartic computed tomography colonography.

METHODS

This study enrolled 284 volunteers with fecal tagging by either diatrizoate or iohexol at an iodine concentration of 13.33 mg/mL and an iodine load of 24 g. Patient acceptance was rated on a 4-point scale of gastrointestinal discomfort. Two gastrointestinal radiologists jointly analyzed image quality, fecal-tagging density and homogeneity, and residual contrast agent in the small intestine. The results were compared by the generalized estimating equation method.

RESULTS

Patient acceptance was comparable between the 2 groups (3.95 ± 0.22 vs 3.96 ± 0.20, P = 0.777). The diatrizoate group had less residual fluid and stool than the iohexol group ( P = 0.019, P = 0.004, respectively). There was no significant difference in colorectal distention, residual fluid, and stool tagging quality between the 2 groups (all P 's > 0.05). The mean 2-dimensional image quality score was 4.59 ± 0.68 with diatrizoate and 3.60 ± 1.14 with iohexol ( P < 0.001). The attenuation of tagged feces was 581 ± 66 HU with diatrizoate and 1038 ± 117 HU with iohexol ( P < 0.001). Residual contrast agent in the small intestine was assessed at 55.3% and 62.3% for the diatrizoate group and iohexol group, respectively ( P = 0.003).

CONCLUSIONS

Compared with iohexol, diatrizoate had better image quality, proper fecal-tagging density, and more homogeneous tagging along with comparable excellent patient acceptance, and might be more suitable for fecal tagging in noncathartic computed tomography colonography.

Advances in CT Colonography for Colorectal Cancer Screening and Diagnosis

CT colonography (CTC) is a validated colorectal cancer test that provides an additional minimally-invasive screening option which is likely to be preferred by some patients. Important examination prerequisites include adequate colonic cleansing and distention. Tagging of residual material aids in the differentiation of true polyps from stool. Low radiation dose technique should be employed routinely for screening studies. Readers must be skilled in the use of both 2D and 3D interpretation methods.

Pilot study on efficacy of reduced cathartic bowel preparation with polyethylene glycol and bisacodyl

AIM: To evaluate the efficacy of reduced cathartic bowel preparation with 2 L polyethylene glycol (PEG)-4000 electrolyte solution and 10 mg bisacodyl enteric-coated tablets for computed tomographic colonography (CTC).

METHODS: Sixty subjects who gave informed consent were randomly assigned to study group A, study group B or the control group. On the day prior to CTC, subjects in study group A were given 20 mL 40% wt/vol barium sulfate suspension before 3 mealtimes, 60 mL 60% diatrizoate meglumine diluted in 250 mL water after supper, and 10 mg bisacodyl enteric-coated tablets 1 h before oral administration of 2 L PEG-4000 electrolyte solution. Subjects in study group B were treated identically to those in study group A, with the exception of bisacodyl which was given 1 h after oral PEG-4000. Subjects in the control group were managed using the same strategy as the subjects in study group A, but without administration of bisacodyl. Residual stool and fluid scores, the attenuation value of residual fluid, and discomfort during bowel preparation in the three groups were analyzed statistically.

RESULTS: The mean scores for residual stool and fluid in study group A were lower than those in study group B, but the differences were not statistically significant. Subjects in study group A showed greater stool and fluid cleansing ability than the subjects in study group B. The mean scores for residual stool and fluid in study groups A and B were lower than those in the control group, and were significantly different. There was no significant difference in the mean attenuation value of residual fluid between study group A, study group B and the control group. The total discomfort index during bowel preparation was 46, 45 and 45 in the three groups, respectively, with no significant difference.

CONCLUSION: Administration of 10 mg bisacodyl enteric-coated tablets prior to or after oral administration of 2 L PEG-4000 electrolyte solution enhances stool and fluid cleansing ability, and has no impact on the attenuation value of residual fluid or the discomfort index. The former is an excellent alternative for CTC colorectum cleansing

Preference for colonoscopy versus computerized tomographic colonography: a systematic review and meta-analysis of observational studies

In recent years, colorectal cancer (CRC) screening using computerized tomographic colonography (CTC) has attracted considerable attention. In order to better understand patient preferences for CTC versus colonoscopy, we performed a systematic review and meta-analysis of the available literature. Data sources included published studies, abstracts and book chapters, in any language, with publication dates from 1995 through February 2012, and with prospective or retrospective enrollment of diagnostic or screening patients who had undergone both procedures and explicit assessment of their preference for colonoscopy versus CTC. A predefined algorithm identified eligible studies using computer and hand searches performed by two independent investigators. We used a mixed effects model to pool preference differences (defined as the proportion of subjects who preferred CTC minus the proportion who preferred colonoscopy for each study). Twenty-three studies met inclusion criteria, totaling 5616 subjects. In 16 of these studies, patients preferred CTC over colonoscopy, while colonoscopy was preferred in three studies. Due to the high degree of heterogeneity, an overall pooled preference difference was not calculated. Stratified analysis revealed that studies published in radiology journals (preference difference 0.590 [95 % CI 0.485, 0.694]) seemed more likely than studies in gastroenterology (0.218 [-0.015-0.451]) or general medicine journals (-0.158 [-0.389-0.072]) to report preference for CTC (p<0.001). 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. Three studies featuring limited bowel preparations for CTC reported marked preference for CTC. There was no evidence of publication bias, while cumulative and exclusion analysis did not show any temporal trend or dominant study. Limitations included data heterogeneity and preference ascertainment limitations. 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.

Evaluation of two minimal-preparation regimes for CT colonography: optimising image quality and patient acceptability

OBJECTIVE

To compare a 2 day bowel preparation regime of barium, iodine and a mild stimulant laxative with a 1 day iodine-only regime for CT colonography (CTC).

METHODS

100 consecutive patients underwent CTC. The first 50 patients (Regime 1) ingested 1 bisacodyl tablet twice a day 3 days before CTC and 1 dose each of 50 ml of barium and 20 ml of iodinated contrast per day starting 2 days before CTC. The second 50 patients (Regime 2) ingested 3 doses of iodinated contrast over 24 h prior to CTC. Volumes of residual stool and fluid, and the effectiveness of stool and fluid tagging, were graded according to methods established by Taylor et al (Taylor S, Slaker A, Burling D, Tam E, Greenhalgh R, Gartner L, et al. CT colonography: optimisation, diagnostic performance and patient acceptability of reduced-laxative regimens using barium-based faecal tagging. Eur Radiol 2008; 18: 32-42). A 3 day low-residue diet was taken by both cohorts. Questionnaires rating the side-effects and burden of the bowel preparation were compared to a control cohort of patients undergoing barium enema.

RESULTS

The proportion of colons producing none/scattered stool (score 1) was 90.3% with Regime 1 and 65.0% with Regime 2 (p<0.005). Any residual stool was significantly better tagged with Regime 1 (score 5), with 91.7% of Regime 1 exhibiting optimum tagging vs 71.3% of Regime 2 (p<0.05). No significant differences in side-effects between the bowel preparation regimes for CTC were elicited. Bowel preparation for barium enema was tolerated significantly worse than both of the CTC bowel preparation regimes.

CONCLUSION

Regime 1, containing a 3 day preparation of a mild laxative, barium and iodine, produced a significantly better prepared colon, with no difference in patient acceptability.

CT colonography: patient tolerance of laxative free fecal tagging regimen versus traditional cathartic cleansing

PURPOSE

The aim of our prospective study was to compare patient tolerance of laxative free fecal tagging regimen (LFT) versus traditional cathartic cleansing (TC).

MATERIALS AND METHODS

264 patients, at average risk for development of colorectal cancer (105 men and 159 women; mean age 62 years ± 5 SD), underwent 32 rows CT colonography. Patients were alternatively placed into 2 study groups: Group 1 (n = 132) followed TC and Group 2 (n = 132) LFT. TC protocol consisted of no fiber diet and Phospho-lax(®) 80 mL in 2 L of water the day before imaging. LFT protocol consisted of no fiber diet and ingestion with meals of 30 mL of water-soluble iodinated contrast agent (Gastrografin(®)) for 2 days before imaging. No frank laxative drugs were administered. All studies were reviewed in a combined fashion, primary 2D followed by 3D endoluminal and dissected views. After the examination all patients were asked to provide a feedback about tolerance to the each bowel preparation. The first 30 patients of each group were also investigated with optical colonoscopy (OC) used as gold standard to confirm our diagnosis (Group 1* and Group 2*).

CONCLUSIONS

LFT reduces discomfort and seems to improve diagnostic accuracy of CTC.

CT colonography without cathartic preparation: positive predictive value and patient experience in clinical practice

OBJECTIVE

To determine the positive predictive value (PPV) for polyps ≥ 6 mm detected at CT colonography (CTC) performed without cathartic preparation, with low-dose iodine faecal tagging regimen and to evaluate patient experience.

METHODS

1920 average-risk patients underwent CTC without cathartic preparation. Faecal tagging was performed by diatrizoate meglumine and diatrizoate sodium at a total dose of 60 ml (22.2 g of iodine).The standard interpretation method was primary 3D with 2D problem solving. We calculated per-patient and per-polyp PPV in relation to size and morphology. All colonic segments were evaluated for image quality (faecal tagging, amount of liquid and solid residual faeces and luminal distension). Patients completed a questionnaire before and after CTC to assess preparation and examination experience.

RESULTS

Per-polyp PPV for detected lesions of ≥ 6 mm, 6-9 mm, ≥ 10 mm and ≥ 30 mm were 94.3%, 93.1%, 94.7% and 98%, respectively. Per-polyp PPV, according to lesion morphology, was 94.6%, 97.3% and 85.1% for sessile, pedunculated and flat polyps, respectively. Per-patient PPV was 92.8%. Preparation without frank cathartics was reported to cause minimal discomfort by 78.9% of patients.

CONCLUSION

CTC without cathartic preparation and low-dose iodine faecal tagging may yield high PPVs for lesions ≥ 6 mm and is well accepted by patients.

KEY POINTS

• Computed tomographic colonography (CTC) without cathartic preparation is well accepted by patients • Cathartic-free faecal tagging CTC yields high positive predictive values • CTC without cathartic preparation could improve uptake of colorectal cancer screening.

National CT colonography trial (ACRIN 6664): comparison of three full-laxative bowel preparations in more than 2500 average-risk patients

OBJECTIVE

The purpose of our study was to compare the effect of three different full-laxative bowel preparations on patient compliance, residual stool and fluid, reader confidence, and polyp detection at CT colonography (CTC).

SUBJECTS AND METHODS

A total of 2531 patients underwent CTC followed by colonoscopy for the American College of Radiology Imaging Network (ACRIN) National CTC Trial. Of this total, 2525 patients used one of three bowel preparations with bisacodyl tablets and stool and fluid tagging: 4 L of polyethylene glycol (PEG); 90 mL of phosphosoda; or 300 mL of magnesium citrate. Patients reported percent compliance with the bowel preparation and radiologists graded each CTC examination for the amount of residual fluid and stool on a scale from 1 (none) to 4 (nondiagnostic). Reader confidence for true-positive findings was reported on a 5-point scale: 1 (low) to 5 (high). Sensitivity and specificity for detecting polyps ≥ 6 mm and ≥ 1 cm compared with colonoscopy were calculated for each preparation.

RESULTS

The most commonly prescribed preparation was phosphosoda (n = 1403) followed by PEG (n = 1020) and magnesium citrate (n = 102). Phosphosoda had the highest patient compliance (p = 0.01), least residual stool (p < 0.001), and highest reader confidence versus PEG for examinations with polyps (p = 0.06). Magnesium citrate had significantly more residual fluid compared with PEG and phosphosoda (p = 0.006). The sensitivity and specificity for detecting colon polyps ≥ 6 mm and ≥ 1 cm did not differ significantly between preparations.

CONCLUSION

Polyp detection was comparable for all three preparations, although phosphosoda had significantly higher patient compliance and the least residual stool.

CT colonography with limited bowel preparation for the detection of colorectal neoplasia in an FOBT positive screening population

Purpose

Aim was to evaluate the accuracy of computed tomography colonography (CTC) for detection of colorectal neoplasia in a Fecal Occult Blood Test (FOBT) positive screening population.

Methods

In three different institutions, consecutive FOBT positives underwent CTC after laxative free iodine tagging bowel preparation followed by colonoscopy with segmental unblinding. Each CTC was read by two experienced observers. For CTC and for colonoscopy the per-polyp sensitivity and per-patient sensitivity and specificity were calculated for detection of carcinomas, advanced adenomas, and adenomas.

Results

In total 22 of 302 included FOBT positive participants had a carcinoma (7%) and 137 had an adenoma or carcinoma ≥10 mm (45%). CTC sensitivity for carcinoma was 95% with one rectal carcinoma as false negative finding. CTC sensitivity for advanced adenomas was 92% (95% CI: 88–96) vs. 96% (95% CI: 93–99) for colonoscopy (P = 0.26). For adenomas and carcinomas ≥10 mm the CTC per-polyp sensitivity was 93% (95% CI: 89–97) vs. 97% (95% CI: 94–99) for colonoscopy (P = 0.17). The per-patient sensitivity for the detection of adenomas and carcinomas ≥10 mm was 95% (95% CI: 91–99) for CTC vs. 99% (95% CI: 98–100) for colonoscopy (P = 0.07), while the per-patient specificity was 90% (95% CI: 86–95) and 96% (95% CI: 94–99), respectively (P < 0.001).

Conclusion

CTC with limited bowel preparation performed in an FOBT positive screening population has high diagnostic accuracy for the detection of adenomas and carcinomas and a sensitivity similar to that of colonoscopy for relevant lesions.

Bowel Preparation Regimen for Computed Tomography Colonography

Purpose

This study was designed to determine whether a reduction in oral contrast dose and a change in timing of administration will result in less residual material in the colonic lumen.

Method

We retrospectively assessed, in a blinded fashion, the amount and nature of residual material in the colon in 40 patients who received computed tomography colonography. Half of the cohort received the standard bowel-preparation regimen, whereas a sex- and age-matched test arm received the modified regimen. A scoring system that consisted of metrics to quantify the nature and extent of residual fluid and solid material was defined. Image analysis was conducted with the investigators blinded to the group assignment of each patient. Three different trained observers independently reviewed and scored the 6 colonic segments in supine and prone positions for each patient in the cohort. In cases in which interobserver discrepancies existed, the observers reanalyzed the images together to come to an agreement on scores.

Results

The new bowel-preparation regimen resulted in significantly less “sticky coat” ( P < .005), a problematic phenomenon in which the colonic mucosa is covered in a thin coating of residual contrast and fecal material. There was no difference in the amount of residual fluid. Fewer masses of stool were noted with the new preparation, but this was not found to be statistically significant.

Conclusion

A new bowel-preparation regimen that consisted of lower quantities of contrast administered earlier in the day preceding computed tomography colonography resulted in a lower incidence of adherent contrast and fecal matter. The reduction of this “sticky coat” problem not only improved radiologic analysis of the colon but may permit same-day therapy via colonoscopy if indicated on imaging.

Reducing the oral contrast dose in CT colonography: evaluation of faecal tagging quality and patient acceptance

AIM

To evaluate the minimal iodine contrast medium load necessary for an optimal computed tomography colonography tagging quality.

MATERIALS AND METHODS

Faecal occult blood test positive patients were randomly selected for one of three iodine bowel preparations: (1) 3 × 50 ml meglumine ioxithalamate (45 g iodine), (2) 4 × 25 ml meglumine ioxithalamate (30 g iodine); or (3) 3 × 25 ml (22.5 g iodine) meglumine ioxithalamate. Two experienced readers assessed the tagging quality per colonic segment on a five-point scale and the presence of adherent stool. Also semi-automatic homogeneity measurements were performed. Patient acceptance was assessed with questionnaires.

RESULTS

Of 70 eligible patients, 45 patients participated (25 males, mean age 62 years). Each preparation group contained 15 patients. The quality of tagging was insufficient (score 1-2) in 0% of segments in group 1; 4% in group 2 (p<0.01 versus group 1); and 5% in group 3 (p=0.06 versus group 1). In group 1 in 11% of the segments adherent stool was present compared with 49% in group 2 and 41% in group 3 (p<0.01, group 2 and 3 versus group 1). Homogeneity was 85, 102 (p<0.01), and 91 SD HU (p=0.26) in groups 1, 2, and 3, respectively. In group 1 two patients experienced no burden after contrast agent ingestion compared to one patient in group 2 and nine patients in group 3 (p=0.017).

CONCLUSION

A dose of 3 × 50 ml meglumine ioxithalamate is advisable for an optimal tagging quality despite beneficial effects on the patient acceptance in patients receiving a lower dose.

Low-fiber diet in limited bowel preparation for CT colonography: Influence on image quality and patient acceptance

OBJECTIVE

The purpose of this study was to determine whether a low-fiber diet is necessary for optimal tagging-only bowel preparation for CT colonography.

SUBJECTS AND METHODS

Fifty consecutively enrolled patients received an iodine bowel preparation: 25 patients used a low-fiber diet and 25 used no special diet. One observer determined the tagging quality per segment on a 5-point scale (1, inhomogeneous tagging; 5, excellent preparation) and the largest size of untagged feces. Semiautomatic measurements of density and homogeneity of residual feces were performed. Patient acceptance was assessed with questionnaires. Per polyp sensitivity for polyps 6 mm in diameter and larger was calculated for two experienced observers.

RESULTS

Tagging quality was scored less than grade 5 in 15 segments (10%) in the low-fiber diet group and in 25 segments (17%) in the unrestricted diet group (p = 0.098). One piece of untagged feces 10 mm in diameter or larger was found in the low-fiber diet group, and 12 were found in the unrestricted diet group (p < 0.001). Automatic measurement of attenuation resulted in a mean value of 594 HU in the low-fiber diet group and 630 HU in the unrestricted diet group (p = 0.297). In the low-fiber diet group, 22% of patients indicated that the bowel preparation was extremely or severely burdensome; 8% of patients in the unrestricted diet group had this response (p = 0.19). Thirty-two polyps 6 mm in diameter or larger were found in the low-fiber diet group and 30 in the unrestricted diet group. Observer 1 had 84% and 77% sensitivity in detecting polyps 6 mm in diameter or larger in the low-fiber diet and unrestricted diet groups, respectively (p = 0.443), and observer 2 had 97% and 83% sensitivity (p = 0.099).

CONCLUSION

Use of a low-fiber diet in bowel preparation for CT colonography results in significantly less untagged feces and shows a trend toward better residue homogeneity.

Limited-preparation CT colonography in frail elderly patients: a feasibility study

OBJECTIVE

Full colonic preparation can be onerous and may be poorly tolerated in frail elderly patients. The purpose of this study was to prospectively assess the image quality and diagnostic yield of limited-preparation CT colonography (CTC) in elderly patients with suspected colorectal cancer who were deemed medically unfit or unsuitable for colonoscopy.

SUBJECTS AND METHODS

A prospective study was performed of 67 elderly patients with reduced functional status referred for CTC. Participants were prescribed a limited bowel preparation consisting of a low-residue diet for 3 days, 1 L of 2% oral diatrizoate meglumine (Gastrografin) 24 hours before CTC, and 1 L of 2% oral Gastrografin over the 2 hours immediately before CTC. No cathartic preparation was administered. All colonic segments were graded from 1 to 5 for image quality (1, unreadable; 2, poor; 3, equivocal; 4, good; 5, excellent) and reader confidence. Clinical and conventional colonoscopy follow-up findings were documented, and all colonic and extracolonic pathologic findings were documented.

RESULTS

Overall image quality and reader confidence in the evaluation of the colon was rated good or excellent in 84% of the colonic segments. Colonic abnormalities were identified in 12 patients (18%), including four colonic tumors, two polyps, and seven colonic strictures. Incidental extraintestinal findings were detected in 43 patients (64%), including nine patients with lesions radiologically consistent with malignancy.

CONCLUSION

Limited-preparation low-dose CTC is a feasible and useful minimally invasive technique with which to evaluate the colon and exclude gross pathology (mass lesions and polyps > 1 cm) in elderly patients with diminished performance status, yielding good to excellent image quality.

Current techniques in the performance, interpretation, and reporting of CT colonography

The technical objective of computed tomographic colonography (CTC) is to acquire high-quality computed tomography images of the cleansed, well-distended colon for polyp detection. In this article the authors provide an overview of the technical components of CTC, from preparation of the patient to acquisition of the imaging data and basic methods of interpretation. In each section, the best evidence for current practices and recommendations is reviewed. Each of the technical components must be optimized to achieve high sensitivity in polyp detection.

Performance of CT colonography in clinical trials

The amount of data accumulated in trials of CT colonography (CTC) has greatly increased in the past decade. The information from these studies is shaping clinical practice and public health policy regarding screening for colorectal cancer (CRC). This article examines the performance of CTC in clinical trials for individuals at average risk and increased risk for CRC. It also addresses the efficacy of CTC after incomplete colonoscopy, when colon preparations are reduced or eliminated, and in academic versus nonacademic environments. The data suggest that CTC is effective especially for the detection of larger lesions and when more advanced imaging technology is used.

CT colonography with decreased purgation: balancing preparation, performance, and patient acceptance

OBJECTIVE

Reduction or elimination of catharsis with fecal tagging enhances the tolerability of CT colonography (CTC) and may increase compliance with colorectal cancer (CRC) screening recommendations. We systematically reviewed studies that prospectively evaluated performance and patient satisfaction with decreased-purgation CTC and with optical colonoscopy.

CONCLUSION

The nine studies reviewed showed moderate-to-good performance for decreased-purgation CTC; however, data are limited, and study design and data presentation are inconsistent. Further study of decreased-purgation CTC and standardization of terminology are needed.

Comparative evaluation of the fecal-tagging quality in CT colonography: barium vs. iodinated oral contrast agent

RATIONALE AND OBJECTIVES

The purpose of this evaluation was to compare the tagging quality of a barium-based regimen with that of iodine-based regimens for computed tomographic (CT) colonography.

MATERIALS AND METHODS

Tagging quality was assessed retrospectively in three different types of fecal-tagging CT colonographic cases: 24 barium-based cases, 22 nonionic iodine-based cases, and 24 ionic iodine-based cases. For the purpose of evaluation, the large intestine was divided into six segments, and the tagging homogeneity of a total of 420 segments (70 patients) was graded by three blinded readers from 0 (heterogeneous) to 4 (homogeneous).

RESULTS

For barium-based cases, the average score for the three readers was 2.4, whereas it was 3.4 for nonionic iodine and 3.6 for ionic iodine. The percentages of segments that were assigned scores of 4 (excellent tagging [100%]) were 11.6%, 61.9%, and 72.9% for the barium-based, nonionic iodine-based, and ionic iodine-based regimens, respectively. The homogeneity scores of iodine-based fecal-tagging regimens were significantly higher than those of the barium-based fecal-tagging regimen (P < .001). The CT attenuation values of tagging in the cases were also assessed: the minimum and maximum values were significantly higher for the iodine-based regimens than for the barium-based regimen (P < .001).

CONCLUSIONS

The iodine-based fecal-tagging regimens provide significantly greater homogeneity in oral-tagging fecal material than the barium-based fecal-tagging regimen. Iodine-based fecal-tagging regimens can provide an appropriate method for use in nonlaxative or minimum-laxative CT colonography.

Comparison of three different iodine-based bowel regimens for CT colonography

OBJECTIVE

The aim of this study was to compare the computed tomographic colonography (CTC) image quality and patient acceptance of three iodine-based faecal tagging bowel preparations in 60 patients undergoing the following regimens: a 2-day regimen of meal-time administration of iodine and phospho-soda (GFPH); a 2-day regimen of meal-time mild laxative, followed by iodine administered 2 h before CTC (SD); and a 2-day regimen of meal-time administration of iodine (GF).

METHODS

Two independent radiologists assessed tagging quality; quantitative measures included the tagged stool density, and computer-aided detection (CAD) false-positive rate.

RESULTS

The GFPH and SD regimens provided better subjective quality than GF (p < 0.001). The latter regimen resulted in a higher proportion of insufficiently tagged segments: the measured average stool density was less than 200 HU in 10.7% in all segments vs 3.6% for SD and <0.5% for GFPH, respectively. Insufficient tagging occurred mostly in the ascending colon and the caecum. The CAD false-positive rate increased following the trend: GFPH < SD < GF (p = 0.00012). GFPH was worse tolerated than SD (p < 0.05).

CONCLUSIONS

Considering preparation quality alone, GFPH was the best regimen, but SD provided the best balance between bowel preparation quality and patient acceptability.

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.

Materials and methods

One hundred consecutive patients underwent CT colonography and colonoscopy with segmental unblinding. The first 50 patients (group 1) ingested 7*50 ml iodinated contrast starting 2 days before CT colonography. The latter 50 patients (group 2) ingested 4*50 ml iodinated contrast starting 1 day before CT colonography. Per colonic segment measurements of residual stool attenuation and homogeneity were performed, and a subjective evaluation of tagging quality (grade 1–5) was done. Independently, two reviewers performed polyp and carcinoma detection.

Results

The tagging density was 638 and 618 HU (p = 0.458) and homogeneity 91 and 86 HU for groups 1 and 2, respectively (p = 0.145). The tagging quality was graded 5 (excellent) in 90% of all segments in group 1 and 91% in group 2 (p = 0.749). Mean per-polyp sensitivity for lesions ≥10 mm was 86% in group 1 and 97% in group 2 (p = 0.355). Patient burden from diarrhoea significantly decreased for patients in group 2.

Conclusions

One-day preparation with meglumine ioxithalamate results in an improved patient acceptability compared with 2-day preparation and has a comparable, excellent image quality and good diagnostic performance.

CT colonography with limited bowel preparation: prospective assessment of patient experience and preference in comparison to optical colonoscopy with cathartic bowel preparation

The purpose of this study was to prospectively 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.

Full-laxative versus minimum-laxative fecal-tagging CT colonography using 64-detector row CT: prospective blinded comparison of diagnostic performance, tagging quality, and patient acceptance

RATIONALE AND OBJECTIVES

To compare prospectively 64-detector-row computed tomographic colonography (CTC) after a full-laxative tagging-based preparation (full preparation) with a minimum-laxative tagging-based preparation (minimum preparation) with respect to diagnostic performance in the detection of polyps, tagging quality, and patient acceptance.

MATERIALS AND METHODS

Consecutive 101 patients at high risk for developing colorectal cancer were alternately assigned to either a full preparation group (n = 51) or a minimum preparation group (n = 50) for fecal-tagging CTC. The full preparation consisted of administration of 2-L polyethylene glycol solution with 20 mL of sodium diatrizoate for fecal tagging. The minimum preparation consisted of ingestion of a total of 45 mL of sodium diatrizoate during the 3 days before and 10 mL of sodium picosulfate solution the night before CT. Colonoscopy was used as the reference standard. We assessed the accuracy of polyp detection and the tagging quality for each preparation. All patients were given questionnaires related to their acceptance.

RESULTS

Per-patient sensitivity, specificity, and positive and negative predictive values for polyps > or = 6 mm were as follows: full preparation group, 97%, 92%, 88%, and 98%, respectively; minimum preparation group, 88%, 68%, 56%, and 92%, respectively. Average visual subjective tagging scores for the full and minimum preparation groups were 94.6% and 76.1%, respectively (P < .0001). Minimum preparation was better tolerated than full preparation.

CONCLUSION

Although full-laxative and minimum-laxative fecal-tagging CTC yielded an equally high sensitivity in the detection of polyps > or = 6 mm, the full-laxative fecal-tagging CTC yielded a better specificity than did the minimum-laxative fecal-tagging CTC. Thus, it is desirable to offer patients an option of either full-laxative fecal-tagging CTC for highest diagnostic accuracy and ability to perform a same-day therapeutic colonoscopy without additional bowel preparation, or minimum-laxative fecal-tagging CTC for those unwilling to undergo full preparation but willing to accept moderate decrease in specificity.