Usefulness of CT colonography in patients with incomplete colonoscopy

Colon Capsule Endoscopy vs. CT Colonography Following Incomplete Colonoscopy: A Systematic Review with Meta-Analysis

Following incomplete colonoscopy (IC) patients often undergo computed tomography colonography (CTC), but colon capsule endoscopy (CCE) may be an alternative. We compared the completion rate, sensitivity and diagnostic yield for polyp detection from CCE and CTC following IC. A systematic literature search resulted in twenty-six studies. Extracted data included inter alia, complete/incomplete investigations and polyp findings. Pooled estimates of completion rates of CCE and CTC and complete colonic view rates (CCE reaching the most proximal point of IC) of CCE were calculated. Per patient diagnostic yields of CCE and CTC were calculated stratified by polyp sizes. CCE completion rate and complete colonic view rate were 76% (CI 95% 68-84%) and 90% (CI 95% 83-95%). CTC completion rate was 98% (CI 95% 96-100%). Diagnostic yields of CTC and CCE were 10% (CI 95% 7-15%) and 37% (CI 95% 30-43%) for any size, 13% (CI 95% 9-18%) and 21% (CI 95% 12-32%) for >5-mm and 4% (CI 95% 2-7%) and 9% (CI 95% 3-17%) for >9-mm polyps. No study performed a reference standard follow-up after CCE/CTC in individuals without findings, rendering sensitivity calculations unfeasible. The increased diagnostic yield of CCE could outweigh its slightly lower complete colonic view rate compared to the superior CTC completion rate. Hence, CCE following IC appears feasible for an introduction to clinical practice. Therefore, randomized studies investigating CCE and/or CTC following incomplete colonoscopy with a golden standard reference for the entire population enabling estimates for sensitivity and specificity are needed.

Accuracy of CT colonography in the preoperative staging of colon cancer: a prospective study of 217 patients

AIM

The purpose of the present study was to evaluate the accuracy of computed tomography colonography (CTC) in the preoperative localization and TN staging of colon cancer. CTC can be an effective technique for preoperative evaluation of colon cancer and could facilitate the selection of high-risk patients who may benefit from neoadjuvant chemotherapy.

METHOD

This was a prospective observational study conducted at a single tertiary-care centre. It involved 217 patients (225 tumours) who had colon cancer and underwent preoperative CTC and elective colectomy. The radiologist determined the TNM stage using postprocessing software with multiplanar images and virtual colonoscopy. The following criteria were analysed for every colon tumour: location, size and signs of direct colon wall invasion. The histopathological findings of the surgical colectomy specimens served as the reference standard for local staging.

RESULTS

CTC detected all tumours and achieved an exact location in 208 cases (92.4%). CTC findings changed the surgical plan in 31 patients (14.3%) following colonoscopy. The accuracy in differentiating T3/T4 vs T1/T2 tumours was 87.1%, with a sensitivity and specificity of 88.5% and 84.1%, respectively (kappa = 0.71). For high-risk tumours (T3 ≥ 5 mm and T4), CTC showed an accuracy, sensitivity and specificity of 82.7%, 86% and 80%, respectively (kappa = 0.65). The accuracy of N-stage evaluation was 69.3%, the sensitivity 74% and the specificity 67.1% (kappa = 0.37).

CONCLUSION

CTC provides accurate information for the assessment of tumour localization and T staging, allowing better surgical planning and also allows the selection of locally advanced tumours that may benefit from new treatments such as neoadjuvant chemotherapy.

ACR Appropriateness Criteria® Colorectal Cancer Screening

This review summarizes the relevant literature regarding colorectal screening with imaging. For individuals at average or moderate risk for colorectal cancer, CT colonography is usually appropriate for colorectal cancer screening. After positive results on a fecal occult blood test or immunohistochemical test, CT colonography is usually appropriate for colorectal cancer detection. For individuals at high risk for colorectal cancer (eg, hereditary nonpolyposis colorectal cancer, ulcerative colitis, or Crohn colitis), optical colonoscopy is preferred because of its ability to obtain biopsies to detect dysplasia. After incomplete colonoscopy, CT colonography is usually appropriate for colorectal cancer screening for individuals at average, moderate, or high risk. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

CT colonography: over two decades from discovery to practice

Since the introduction of CT colonography (CTC) in the mid-1990s, there have been continuous advancements in the examination technique and advanced visualization software for interpretation. This review will cover the origins of CTC as a natural extension of abdominal CT imaging, and discuss the evolution of CTC through the subsequent clinical phases of feasibility, validation, and implementation.

Virtual Colonoscopy in Colorectal Cancer Screening

Colorectal cancer is the third most commonly diagnosed tumor in both males and females in the United States. Current modalities for colorectal cancer screening include fecal occult blood testing, flexible sigmoidoscopy, double-contrast barium enema, and colonoscopy. Virtual colonoscopy is a promising new method for assessing the entire colon. Vining and Gelfand first described this technique in 1994. Since then, virtual colonoscopy has been shown to be extremely safe and well tolerated by patients. Indications for virtual colonoscopy include screening for polyps, incomplete or failed colonoscopy, and preoperative assessment of the colon proximal to an occlusive cancer or even redundant fixed or stenotic colon that cannot be endoscopically traversed. Virtual colonoscopy may dramatically increase patient participation in screening programs, leading to early diagnosis of colorectal cancer. Although virtual colonoscopy seems a potentially attractive screening method for colorectal cancer, the cost-effectiveness of this method is yet to be determined.

CT colonography after incomplete optical colonoscopy: bowel preparation quality at same-day vs. deferred examination

PURPOSE

To objectively compare the volume, density, and distribution of luminal fluid for same-day oral-contrast-enhanced CTC following incomplete optical colonoscopy (OC) vs. deferred CTC on a separate day utilizing a dedicated CTC bowel preparation.

METHODS

HIPAA-compliant, IRB-approved retrospective study compared 103 same-day CTC studies after incomplete OC (utilizing 30 mL oral diatrizoate) against 151 CTC examinations performed on a separate day after failed OC using a dedicated CTC bowel preparation (oral magnesium citrate/dilute barium/diatrizoate the evening before). A subgroup of 15 patients who had both same-day CTC and separate-day routine CTC was also identified and underwent separate analysis. CTC exams were analyzed for opacified fluid distribution within the GI tract, as well as density and volume. Data were analyzed utilizing Kruskal-Wallis and Wilcoxon Signed Rank tests.

RESULTS

Opacified luminal fluid extended to the rectum in 56% (58/103) of same-day CTC vs. 100% (151/151) of deferred separate-day CTC (p < 0.0001). For same-day CTC, contrast failed to reach the colon in 11% (11/103) and failed to reach the left colon in 26% (27/103). Volumetric colonic fluid segmentation for fluid analysis (successful in 80 same-day and 147 separate-day cases) showed significantly more fluid in the same-day cohort (mean, 227 vs. 166 mL; p < 0.0001); the actual difference is underestimated due to excluded cases. Mean colonic fluid attenuation was significantly lower in the same-day cohort (545 vs. 735 HU; p < 0.0001). Similar findings were identified in the smaller cohort with direct intra-patient CTC comparison.

CONCLUSIONS

Dedicated CTC bowel preparation on a separate day following incomplete OC results in a much higher quality examination compared with same-day CTC.

Differential Diagnosis of Colonic Strictures: Pictorial Review with Illustrations from Computed Tomography Colonography

Strictures of the colon can lead to significant morbidity requiring surgical management. The etiology of strictures is broad and generally categorized as benign, malignant, or pseudostrictures. Computed tomography (CT) is a crucial imaging modality in the assessment and characterization of colonic pathologies but colonoscopy remains the diagnostic gold standard. However, in the setting of incomplete colonoscopy due to strictures, the imaging features of CT will be relied on. This review will focus on the CT features of different colon pathologies leading to strictures and will be illustrated with images from 10 years of experience with CT colonography at our institutions from 2002-2012 (Hotel Dieu Hospital, Queen's University and Mount Sinai Hospital, University of Toronto).

Fecal tag CT colonography with a limited 2-day bowel preparation following incomplete colonoscopy

PURPOSE

This study aimed to assess the feasibility and patient tolerance of a 2-day limited fecal tag bowel preparation in computed tomographic colonography (CTC) performed for incomplete conventional colonoscopy (CC) patients.

MATERIALS AND METHODS

Seventy-five patients who underwent a CTC examination fbecause of incomplete CC were included. A low-residue diet was given for 2 days before CTC. Fecal tagging (FT) was done using a barium sulfate suspension. The quality of the preparation, success of tagging and patient experience with the bowel preparation were investigated.

RESULTS

Four hundred fifty bowel segments were evaluated. The number of solid stool balls of 6-9 mm size was 284; the corresponding figure was 93 for solid stool balls ≥ 10 mm. Residual fluid was present in about one-third of the segments. The fecal tagging efficacy for ≥ 6 mm residual stool balls was 92 %. Overall, 16 (21.3 %) patients presented with colonic lesions at CTC. Three out of four colonic mass lesions had not been diagnosed with CC. Most patients reported mild discomfort.

CONCLUSION

FT-CTC performed after a limited 2-day bowel preparation seems to be a technically feasible, safe and acceptable procedure that allows a complete a colonic study in incomplete CC patients.

Comparison of a 4-Day versus 2-Day Low Fiber Diet Regimen in Barium Tagging CT Colonography in Incomplete Colonoscopy Patients

Our aim was to compare the amount of residual feces, residual fluid, the tagging quality, and patient compliance using 4-day versus 2-day low fiber diet regimen in barium tagging CT colonography in incomplete colonoscopy patients. Methods. A total of 101 patients who underwent CT colonography were assigned to 2-day diet group (n = 56) and 4-day diet group (n = 45). Fecal tagging was achieved with barium sulphate while bisacodyl and sennoside B were used for bowel preparation. Residual solid stool was divided into two groups measuring <6 mm and ≥6 mm. We graded the residual fluid, tagging quality for solid stool, and fluid per bowel segment. We performed a questionnaire to assess patient compliance. Results. 604 bowel segments were evaluated. There was no significant difference between 2-day and 4-day diet groups with respect to residual solid stool, residual fluid, tagging quality for stool, and fluid observed in fecal tag CT colonography (P > 0.05). The prevalence of moderate discomfort was significantly higher in 4-day group (P < 0.001). Conclusion. Our study shows that 2-day limited bowel preparation regimen for fecal tag CT colonography is a safe and reasonable technique to evaluate the entire colon, particularly in incomplete conventional colonoscopy patients.

CT-colonography after incomplete colonoscopy: what is the diagnostic yield?

BACKGROUND

Computed tomography-colonography is a diagnostic modality that can be used when the colon is not completely intubated during colonoscopy. It may have the additional advantage that information on extracolonic lesions can be obtained.

OBJECTIVE

The aim of this study was to investigate the yield of CT-colonography of relevant intra- and extracolonic findings in patients after incomplete colonoscopy.

DESIGN

This was an observational, retrospective study.

DATA SOURCES

Data were be obtained from standardized radiology and endoscopy reports and electronic medical records.

STUDY SELECTION

In total, 136 consecutive CT-colonographies performed after incomplete colonoscopy were evaluated.

MAIN OUTCOME MEASURES

All intra- and extracolonic findings on CT-colonography were recorded and interpreted for clinical relevance, and it was determined whether further diagnostic and/or therapeutic workup was indicated.

RESULTS

Major indications for colonoscopy included iron-deficiency anemia (25.7%), hematochezia (20.6%), change in bowel habits (18.4%), and colorectal cancer screening or surveillance (11.0%). Major reasons for incomplete colonoscopy were a fixed colon (34.6%) and strong angulation of the sigmoid colon (17.6%). Introduction of the colonoscope was limited to the left-sided colon in 53.7% of cases. Incomplete colonoscopy detected colorectal cancer in 12 (8.8%) patients and adenomatous polyps in 27 (19.9%) patients. CT-colonography after incomplete colonoscopy additionally revealed 19 polyps in 15 (11.0%) and a nonsynchronous colorectal cancer in 4 (2.9%) patients. CT-colonography also detected extracolonic findings with clinical consequences in 8 (5.9%) patients, including fistulizing diverticulitis (n = 3), gastric tumor (n = 2), liver abscess (n = 1), osteomyelitis (n = 1), and an infected embolus in both renal arteries (n = 1).

LIMITATIONS

This study was limited by the lack of confirmation of intraluminal CT-colonography findings in a subset of patients.

CONCLUSIONS

Computed tomography-colonography can be of added value in patients with incomplete colonoscopy, because it revealed 27 relevant additional (both intra- and extracolonic) lesions in 19.1% of patients. In cases where CT-colonography detected colorectal cancer after incomplete colonoscopy, it can also be used for staging purposes.

Contrast-enhanced computed tomography colonography in preoperative distinction between T1-T2 and T3-T4 staging of colon cancer

RATIONALE AND OBJECTIVES

To predict the T stage of nonrectal colon cancer using contrast-enhanced computed tomography colonography.

MATERIALS AND METHODS

Sixty-one patients with 67 nonrectal colon cancers consecutively underwent contrast-enhanced computed tomography colonography after an incomplete colonoscopy. Two readers evaluated wall deformity and perilesional fat abnormality on three-dimensional double contrast enema-like views and multiplanar reconstructions. Pathology was used as the standard of reference. McNemar, Fisher, and Cohen κ statistics were used.

RESULTS

At pathologic examination, we found the following stages: T1 (n = 5), T2 (n = 10), T3 (n = 41), T4a (n = 6), and T4b (n = 5). Intraobserver and interobserver reproducibilities were almost perfect for wall deformity (κ = 1.00 and κ = 0.88, respectively), substantial for perilesional fat abnormality (κ = 0.79 and κ = 0.74, respectively). Using the results of the more experienced reader, accuracy of wall deformity ≥50% (apple-core) alone for T ≥ 3 was 62 of 67 (0.93, 95% confidence interval [CI] 0.83-0.97) and that of perilesional fat abnormality alone was 37 of 67 (0.55, 95% CI 0.43-0.67) (P < .001). Predictive value for ≥ T3 of the association wall deformity ≥50% with perilesional fat abnormality was 22 of 22 (1.00, 95% CI 0.85-1.00), higher, but not significantly, than that of wall deformity ≥50% with normal perilesional fat 29 of 33 (0.88, 95% CI 0.72-0.97) (P = .148, Fisher exact test).

CONCLUSIONS

The presence of apple-core wall deformity, regardless of perilesional fat abnormality, is highly predictive of stage T3 or higher.

Virtual colonoscopy: Utility, impact and overview

Computed tomography (CT) colonoscopy is a well-established technique for evaluation of colorectal cancer. Significant advances have been made in the technique of CT colonoscopy since its inception. Excellent results can be achieved in detecting both colorectal cancer and significant sized polyps as long as a meticulous technique is adopted while performing CT colonoscopy. Furthermore, it is important to realize that there is a learning curve involved in interpreting these studies and adequate experience is essential to achieve high sensitivity and specificity with this technique. Indications, contraindications, technique and interpretation, including potential pitfalls in CT colonoscopy imaging, are reviewed in this article. Recent advances and the current role of CT colonoscopy in colorectal cancer screening are also discussed.

Incomplete colonoscopy: maximizing completion rates of gastroenterologists

BACKGROUND

Cecal intubation is one of the goals of a quality colonoscopy; however, many factors increasing the risk of incomplete colonoscopy have been implicated. The implications of missed pathology and the demand on health care resources for return colonoscopies pose a conundrum to many physicians. The optimal course of action after incomplete colonoscopy is unclear.

OBJECTIVES

To assess endoscopic completion rates of previously incomplete colonoscopies, the methods used to complete them and the factors that led to the previous incomplete procedure.

METHODS

All patients who previously underwent incomplete colonoscopy (2005 to 2010) and were referred to St Paul's Hospital (Vancouver, British Columbia) were evaluated. Colonoscopies were re-attempted by a single endoscopist. Patient charts were reviewed retrospectively.

RESULTS

A total of 90 patients (29 males) with a mean (± SD) age of 58 ± 13.2 years were included in the analysis. Thirty patients (33%) had their initial colonoscopy performed by a gastroenterologist. Indications for initial colonoscopy included surveillance or screening (23%), abdominal pain (15%), gastrointestinal bleeding (29%), change in bowel habits or constitutional symptoms (18%), anemia (7%) and chronic diarrhea (8%). Reasons for incomplete colonoscopy included poor preparation (11%), pain or inadequate sedation (16%), tortuous colon (30%), diverticular disease (6%), obstructing mass (6%) and stricturing disease (10%). Reasons for incomplete procedures in the remaining 21% of patients were not reported by the referring physician. Eighty-seven (97%) colonoscopies were subsequently completed in a single attempt at the institution. Seventy-six (84%) colonoscopies were performed using routine manoeuvres, patient positioning and a variable-stiffness colonoscope (either standard or pediatric). A standard 160 or 180 series Olympus gastroscope (Olympus, Japan) was used in five patients (6%) to navigate through sigmoid diverticular disease; a pediatric colonoscope was used in six patients (7%) for similar reasons. Repeat colonoscopy on the remaining three patients (3%) failed: all three required surgery for strictures (two had obstructing malignant masses and one had a severe benign obstructing sigmoid diverticular stricture).

CONCLUSION

Most patients with previous incomplete colonoscopy can undergo a successful repeat colonoscopy at a tertiary care centre with instruments that are readily available to most gastroenterologists. Other modalities for evaluation of the colon should be deferred until a second attempt is made at an expert centre.

Patients' preferences about follow-up of medium size polyps detected at screening CT colonography

PURPOSE

To evaluate patients' preferences regarding follow-up of medium size polyps detected at screening CT colonography (CTC).

METHODS AND MATERIALS

193 C-RADS2 asymptomatic patients were asked to fill in a form explaining the indications, technique and potential complications of CTC, and were invited to choose their preferred examination technique (CTC or optical colonoscopy: OC) and their follow-up interval by repeated consultations at 3-month intervals. The follow-up interval for CTC and OC was recorded.

RESULTS

87/193 C-RADS2 patients (45.1%) accepted follow-up. Average time interval for follow-up was comparable between CTC and OC (9.00 ± 4.24 vs. 9.00 ± 4.39 months, respectively; P = 0.7188). No patients chose to undergo a 3-year follow-up with either CTC or OC. Most patients elected to have follow-up with either CTC or OC before 18 months rather than later (P = 0.0004).

CONCLUSIONS

A substantial fraction of C-RADS2 patients prefer to undergo immediate OC and polyp removal rather than follow-up, and the majority of those accepting follow-up are willing to wait for less than 18 months. Such findings may suggest a revision of the proposed C-RADS2 category.

Performing an additional decubitus series at CT colonography

PURPOSE

To determine the rate and associated factors for acquiring a decubitus series at CT colonography (CTC), in addition to the standard supine and prone series.

MATERIALS AND METHODS

CTC examinations read centrally at one institution but performed at three different centers in 6,380 adults were reviewed to determine the frequency of an additional decubitus series. Results were analyzed according to study indication (primary screening vs. diagnostic for incomplete colonoscopy), practice site (academic vs. community), patient age, gender, body mass index (BMI), and temporal variation. At all sites, the CT technologist determined the need for an additional decubitus series, with infrequent radiologist input in select cases.

RESULTS

The frequency for the CT technologist to obtain a decubitus series at screening was 9.7% (578/5,952), compared with 22.9% (98/428) following failed colonoscopy (P < 0.001). The decubitus rate for screening at the academic center (9.4%, 550/5,871) was significantly lower than the community hospitals (34.6% combined, 28/81) (P < 0.001). The rate progressively increased with age, from 5.0% under age 50 to 28.0% over age 80. No significant difference was seen between men and women (10.3 vs. 9.2%), but a strong correlation existed with increased BMI, rising to >25% for BMI over 40. Marked temporal variation existed at the academic center, with quarterly rates ranging from 0 to 17%.

CONCLUSIONS

The frequency for performing a third series at CTC varies considerably according to indication, practice site, patient age, BMI, and time. These results have important implications for clinical practice, including the need for improved training and feedback for CT technologists.

Role of CT colonography in symptomatic assessment, surveillance and screening

INTRODUCTION

When 'whole colonic imaging' is indicated, clinicians must decide between optical colonoscopy, barium enema and CT colonography (CTC). CTC is a relatively new technique which has become increasingly accessible in the UK over the past 5 years. As radiologists have gained experience and scanning parameters have standardised, there have been substantial improvements in both the accuracy and safety of CTC.

METHODS

We review evidence from observational studies and randomised trials, and draw on expert opinion, to provide a comprehensive discussion of the current role of CTC in both symptomatic and asymptomatic individuals.

CONCLUSIONS

The emergence of CTC could soon entirely obviate the need for barium enema. CTC now has a complementary role alongside colonoscopy in symptomatic patients and a possible future role in colorectal cancer screening in the UK.

[CT colonography: what radiologists need to know]

In 2008, CT colonography was approved by the American Cancer Society as a technique for screening for colorectal cancer. This approval should be considered an important step in the recognition of the technique, which although still relatively new is already changing some diagnostic algorithms. This update about CT colonography reports the quality parameters necessary for a CT colonographic study to be diagnostic and reviews the technical innovations and colonic preparation for the study. We provide a brief review of the signs and close with a discussion of the current indications for and controversies about the technique.

Patient acceptability of CT colonography compared with double contrast barium enema: results from a multicentre randomised controlled trial of symptomatic patients

OBJECTIVES

To determine patient acceptability of barium enema (BE) or CT colonography (CTC).

METHODS

After ethical approval, 921 consenting patients with symptoms suggestive of colorectal cancer who had been randomly assigned and completed either BE (N = 606) or CTC (N = 315) received a questionnaire to assess experience of the clinical episode including bowel preparation, procedure and complications. Satisfaction, worry and physical discomfort were assessed using an adapted version of a validated acceptability scale. Non-parametric methods assessed differences between the randomised tests and the effect of patient characteristics.

RESULTS

Patients undergoing BE were significantly less satisfied (median 61, interquartile range [IQR] 54-67 vs. median 64, IQR 56-69; p = 0.003) and experienced more physical discomfort (median 40, IQR 29-52 vs. median 35.5, IQR 25-47; p < 0.001) than those undergoing CTC. Post-test, BE patients were significantly more likely to experience 'abdominal pain/cramps' (68% vs. 57%; p = 0.007), 'soreness' (57% vs. 37%; p < 0.001), 'nausea/vomiting' (16% vs. 8%; p = 0.009), 'soiling' (31% vs. 23%; p = 0.034) and 'wind' (92% vs. 84%; p = 0.001) and in the case of 'wind' to also rate it as severe (27% vs. 15%; p < 0.001).

CONCLUSION

CTC is associated with significant improvements in patient experience. These data support the case for CTC to replace BE.

Spiral overtube-assisted colonoscopy after incomplete colonoscopy in the redundant colon

BACKGROUND

A redundant colon can lead to incomplete colonoscopy. A variety of tools and techniques are available to complete colonoscopy but have limitations.

OBJECTIVE

To determine the feasibility and safety of using a spiral overtube to complete a difficult colonoscopy.

DESIGN

Retrospective review of a prospectively collected database.

SETTING

Single tertiary institution.

PATIENTS

Twenty-four patients with incomplete colonoscopy because of redundant colons underwent 26 procedures. The median age was 68 years, and 58% were men.

INTERVENTIONS

All patients underwent colonoscopy performed with a 90-cm flexible threaded overtube and a variable-stiffness pediatric colonoscope. Four individuals (18%) required exchanging the colonoscope for an enteroscope.

MAIN OUTCOME MEASUREMENTS

Successful cecal intubation, polyp identification and removal, time to reach the cecum, sedation needed, and complications.

RESULTS

Cecal intubation was achieved in 22 patients (92%). Failures occurred in 2 patients with large hernias. The median time from insertion of the colonoscope to reaching the cecum was 14.5 minutes. All procedures were performed by using conscious sedation with midazolam (median dose 7 mg) and fentanyl (median dose 150 μg). Significant findings were encountered in 17 of 22 patients (77%) including 1 cancer and 2 advanced polyps. A median of 3 polyps was removed from each patient who had polyps. All noncancerous polyps were removed during the procedure. There were no complications.

LIMITATIONS

Retrospective design, no control group, single center.

CONCLUSION

Spiral overtube-assisted colonoscopy can enable cecal intubation in the majority of patients in whom standard colonoscopy fails because of a redundant colon.

ACR Colon Cancer Committee white paper: status of CT colonography 2009

PURPOSE

To review the current status and rationale of the updated ACR practice guidelines for CT colonography (CTC).

METHODS

Clinical validation trials in both the United States and Europe are reviewed. Key technical aspects of the CTC examination are emphasized, including low-dose protocols, proper insufflation, and bowel preparation. Important issues of implementation are discussed, including training and certification, definition of the target lesion, reporting of colonic and extracolonic findings, quality metrics, reimbursement, and cost-effectiveness.

RESULTS

Successful validation trials in screening cohorts both in the United States with ACRIN and in Germany demonstrated sensitivity > or = 90% for patients with polyps >10 mm. Proper technique is critical, including low-dose techniques in screening cohorts, with an upper limit of the CT dose index by volume of 12.5 mGy per examination. Training new readers includes the requirement of interactive workstation training with 2-D and 3-D image display techniques. The target lesion is defined as a polyp > or = 6 mm, consistent with the American Cancer Society joint guidelines. Five quality metrics have been defined for CTC, with pilot data entered. Although the CMS national noncoverage decision in May 2009 was a disappointment, multiple third-party payers are reimbursing for screening CTC. Cost-effective modeling has shown CTC to be a dominant strategy, including in a Medicare cohort.

CONCLUSION

Supported by third-party payer reimbursement for screening, CTC will continue to further transition into community practice and can provide an important adjunctive examination for colorectal screening.

Noninvasive radiologic imaging of the large intestine: a valuable complement to optical colonoscopy

PURPOSE OF REVIEW

Radiologic imaging of the large intestine continues to evolve and expand the potential for noninvasive diagnosis. The aim of this review is to provide an update on current and emerging clinical capabilities for a variety of radiologic diagnostic imaging tools for evaluating the colon and rectum.

RECENT FINDINGS

The utility of computed tomography for the evaluation of symptomatic inflammatory and neoplastic conditions of the colon is well established, but the clinical role of computed tomography colonography is rapidly evolving. In addition to a number of diagnostic indications, computed tomography colonography is emerging as a potential frontline colorectal screening test for cancer prevention. MRI has become increasingly valuable for rectal cancer staging and inflammatory bowel disease but has yet to gain momentum for polyp evaluation. PET imaging has been primarily utilized for oncologic indications, but also holds considerable potential for inflammatory conditions. Other imaging modalities, such as the barium enema, conventional radiography, and ultrasound, play a much more limited role.

SUMMARY

Advances in radiologic imaging of the colorectum will continue to expand the capabilities and clinical indications for noninvasive diagnosis, allowing for a greater emphasis on the complementary roles of tissue sampling and therapy with optical colonoscopy.

CT colonography: Friend or foe of practicing endoscopists

AIM

To investigate the perceived impact of computed tomographic colonography (CTC) on endoscopists' current and future practice.

METHODS

A 21-question survey was mailed to 1570 randomly chosen American Society for Gastrointestinal Endoscopy (ASGE) members. Participants reported socio-demographics, colonoscopy volume, percentage of colonoscopies performed for screening, and likelihood of integration of CTC into their practice.

RESULTS

A total of 367 ASGE members (23%) returned the questionnaire. Respondents were predominantly male (> 90%) and white (83%) with an average age of 49 years. Most respondents (58%) had no plans to incorporate CTC into daily practice and only 7% had already incorporated CTC into daily practice. Private practice respondents were the least likely to incorporate this modality into their daily practice (P = 0.047). Forty-three percent of participants were willing to take courses on CTC reading, particularly those with the highest volume of colonoscopy (P = 0.049). Forty percent of participants were unsure of CTC's impact on future colonoscopy volume while 21% and 18% projected a decreased and increased volume, respectively. The estimated impact of CTC volume varied significantly by age (P = 0.002). Respondents > 60 years felt that CTC would increase colonoscopy, whereas those < 40 years thought CTC would ultimately decrease colonoscopy.

CONCLUSION

Practicing endoscopists are not enthusiastic about the incorporation of CTC into their daily practice and are unsure of its future impact on their practice.

[Evaluation of computed tomographic colonography for detection of colorectal polyps]

BACKGROUND

Computed tomographic colonography has been proposed for detection of colorectal polyps instead of colonoscopy in colorectal cancer screening programs.

AIM

To evaluate the performance of computed tomographic colonography in the detection of colorectal polyps with colonoscopy used as the gold standard.

METHODS

We prospectively studied 20 patients at high risk for colorectal neoplasia (14 men and 6 women; mean age, 55 years and 59 years). Computed tomographic colonography was performed immediately before colonoscopy. We inserted a rectal balloon catheter and insufflated the colon with room air to the level that a good distension was observed. Twenty milligrams of hioscin was given immediately before computed tomographic imaging of the abdomen and pelvis in order to minimize the degree of smooth-muscle spasm and peristalsis and to reduce the patient's discomfort.

RESULTS

Computed tomographic colonography images were considered satisfactory in all cases. Colonoscopy detected 85 polyps in 19 of 20 patients (95%). All the observed polyps were successfully removed and examined histologically. The radiological examination correctly identified 8 of 10 polyps 10 mm or more in diameter, 2 of 19 (18,2%) with 5-9 mm, and just 1 of 53 <5mm (9,1%). Seventeen of the 43 adenomatous polyps were > or =5 mm. Eight (47%) were correctly identified on computed tomographic colonography. None of the neoplasias <5 mm were identified on colonography. Nineteen patients preferred colonoscopy in the event of having to repeat on of the two examinations.

CONCLUSION

For the detection of colorectal polyps, computed tomographic colonography seems to be useful only when the result is positive, as the negative results of this examination cannot eliminate the presence of these lesions.

Virtual endoscopy using CT scan

The term virtual endoscopy refers to using either spiral computed tomography (CT colonography) or magnetic resonance scanning (MR colonography) combined with computer technology to produce high-resolution two- and three-dimensional imaging of the large bowel. Current CT techniques require meticulous bowel preparation and gas insufflation prior to the examination. The advantages of CT colonography over conventional colonography include safety, its ability to demonstrate the entire large bowel in almost all patients, even following incomplete endoscopy, to accurately localize lesions, and to examine the entire colon in patients with obstructing tumors. Additionally, CT colonography allows simultaneous preoperative tumor staging. Screening for colorectal polyps is a controversially discussed indication for CT colonography. Sensitivity and specificity range widely and decrease with decreasing polyp size. However, better results can be achieved using multidetector technology. Most frequently, the examination is well tolerated and assessed by patients to be more acceptable than conventional colonoscopy. There are no reported complications from CT colonography. The procedure requires a scan time of about 25 to 30 seconds with new multidetector CT scanners, and sedation is not used. Currently, CT colonography is less cost-effective than conventional endoscopy. Another disadvantage is the relatively high irradiation exposure associated with CT colonography. Therefore, at the moment, this technique does not appear ready to be included in general screening strategies. However, ongoing and future improvements may prove its value in colorectal examination strategies.

[Indications for and results of CT colonography: from screening to the symptomatic patient]

CT colonography (CTC) is also referred to as virtual colonoscopy and is being used with increasing frequency in radiological practice. While there are still no generally accepted, clear-cut indications for its use in mass colorectal cancer screening, there is evidence that this investigation is useful in patients in whom colonoscopy has not been successful or who have known stenotic lesions in the colon. Recent results of significant comparative studies of CTC and conventional colonoscopy will have some influence on the future place of CTC in screening for cancer of the bowel; they show the great potential of CT-aided bowel examination.

Use of modified multidetector CT colonography for the evaluation of acute and subacute colon obstruction caused by colorectal cancer: a feasibility study

PURPOSE

This study was designed to evaluate the feasibility of using CT colonography with a modified procedural protocol for diagnosis and cancer staging in patients with suspected acute or subacute colon obstruction caused by colorectal cancer.

METHODS

Following colonic cleansing with lukewarm water enemas, thin-collimation CT colonography was performed on 47 patients (15 women and 32 men, mean age, 68 years) in the precontrast prone position and in the supine position after the intravenous administration of a contrast agent. The surgical and pathologic findings served as a reference standard.

RESULTS

In 44 of 47 patients, colon distention was caused by obstruction, and pathologic examination confirmed colorectal cancer in 41 of these 44 patients. CT colonography correctly located all tumors and successfully identified noncancerous causes of colon distention in five patients. The overall accuracy of staging was 97.6 percent for the T category, 73.2 percent for N, and 100 percent for M. Two synchronous colorectal cancers were correctly identified.

CONCLUSIONS

When appropriate protocol modifications regarding colon cleansing and air insufflation are made to take the clinical situation into account, CT colonography is a technically feasible, accurate, and well-tolerated method for tumor evaluation and cancer staging in patients with acute and subacute colon obstruction.

Detection of occult colonic perforation before CT colonography after incomplete colonoscopy: perforation rate and use of a low-dose diagnostic scan before CO2 insufflation

OBJECTIVE

The purpose of this study was to obtain a low-dose CT scan before CT colonography to estimate the prevalence of occult colonic perforation among patients referred for same-day or next-day CT colonography after incomplete colonoscopy.

MATERIALS AND METHODS

Two hundred sixty-two patients (74 men, 188 women; mean age, 64 years; range, 21-92 years) consecutively referred for same-day or next-day CT colonography after incomplete colonoscopy underwent low-dose diagnostic CT before rectal tube insertion and CO(2) insufflation.

RESULTS

Perforation was found on the low-dose CT scans of two of the 262 patients (0.8%; 95% CI, 0.1-2.7%). One of these patients had no symptoms; the other had mild abdominal discomfort at the time of CT.

CONCLUSION

The rate of occult colonic perforation after incomplete colonoscopy may be significant. For patients referred for CT colonography after incomplete endoscopy, use of low-dose diagnostic CT before rectal tube insertion and insufflation is indicated.

Current role and future potential of computed tomographic colonography for colorectal polyp detection and colon cancer screening-incidental findings

AIM

In this retrospective study, we assess the current role and future potential of computed tomographic (CT) colonography as a viable alternative imaging tool for colorectal polyp detection and colon cancer screening.

MATERIALS AND METHODS

Twenty patients have undergone virtual colonographic examinations with 64-multidetector-row spiral CT (MDCT), and three-dimensional images were created on a separate workstation that had the appropriate software for image processing. Images were reviewed by a radiologist, and anatomic division of the entire colon was used to locate the suspected lesions. Characteristics of bowel preparation, intracolonic, extracolonic, and incidental findings were noted, too.

RESULTS

Ten of the 20 patients (50%) had a positive CT colonography for polypoid lesions. Those lesions were distributed into the cecum (4 cases), colon ascendens (2 cases), colon descendens (2 cases), and sigma (2 cases). In 80%, bowel preparation was good, in 15% moderate, and in 5% inadequate. Furthermore, CT scan noted in total 20 incidental findings.

CONCLUSION

CT colonography is currently a viable alternative imaging tool for colorectal polyp detection. There are several clinical situations where CT colonography may play an important role in patient care. These include for example evaluation of the colon after an incomplete conventional colonoscopic examination or evaluation in patients who are clinically unfit to undergo conventional colonoscopy. At centers where there is expertise in data acquisition and interpretation, CT colonography is being offered as a routine imaging examination. With continued improvements in bowel preparation, colonic distention, and CT colonography interpretation by sufficient numbers of radiologists this technology might have a substantial influence on colon cancer screening.

CT colonography after incomplete colonoscopy in subjects with positive faecal occult blood test

AIM: To report our experience with computed tomography colonography (CTC) systematically performed in subjects with positive faecal occult blood test (FOBT) and an incomplete colonoscopy in the setting of a population-based screening for colorectal cancer (CRC).

METHODS: From April 2006 to April 2007, 43 290 individuals (age range 50-70) who adhered to the regional screening program for the prevention of CRC underwent immunochemical FOBT. FOBT was positive in 1882 subjects (4.3%). 1463 (77.7%) of these subjects underwent colonoscopy, 903 performed in a single center. Of 903 colonoscopies 65 (7.2%) were incomplete. Forty-two of these subjects underwent CTC. CTC was performed with a 16-MDCT scanner after standard bowel prep (polyethylene glycole) in both supine and prone position. Subjects whose CTC showed polyps or masses were referred to the endoscopist for repeat colonoscopy under sedation or underwent surgery. Per-lesion and per-segment positive predictive values (PPV) were calculated.

RESULTS: Twenty-one (50%) of 42 CTCs showed polyps or masses. Fifty-five of these subjects underwent a repeat colonoscopy, whereas 2 subjects underwent surgery for colonic masses of indeterminate nature. Four subjects refused further examinations. CTC correctly identified 2 colonic masses and 20 polyps. PPV for masses or polyps greater than 9 mm was of 87.5%. Per-lesion and per-segment PPV were, respectively, 83.3% and 83.3% for polyps greater or equal to 10 mm, and 77.8% and 85.7% for polyps of 6-9 mm.

CONCLUSION: In the context of a screening program for CRC based on FOBT, CTC shows high per-segment and per-lesion PPV for colonic masses and polyps greater than 9 mm. Therefore, CTC has the potential to become a useful technique for evaluation of the non visualized part of the colon after incomplete colonoscopy.

Usefulness of virtual colonoscopy in the diagnosis of symptomatic large colonic lipomas

Lipomas of the colon are uncommon tumour of the gastrointestinal tract, but cause diagnostic difficulty when they are symptomatic. We reported two cases of symptomatic, large colonic lipoma. Colonoscopy was incomplete because of the narrowing lumen caused by lipomas. By the help of computed tomography colonography/virtual colonoscopy, colonic lipomas were diagnosed correctly, but also proximal colon was examined.

CT colonography in 546 patients with incomplete colonoscopy

PURPOSE

To retrospectively evaluate the positive predictive value (PPV) of computed tomographic (CT) colonography performed in patients who were referred for further examination after incomplete colonoscopy.

MATERIALS AND METHODS

This HIPAA-compliant retrospective study was approved by the institutional review board; informed consent was waived. We identified 546 consecutive patients (mean age, 64.1 years; 401 [73.4%] women) who underwent CT colonography after incomplete colonoscopy between November 1999 and December 2002. A retrospective chart review was performed if CT colonography depicted endoscopically nonvisualized lesions 6 mm or greater in diameter. Repeat colonoscopy rate, endoluminal findings, and PPV of CT colonography were determined. Subsequent colonoscopic findings were used as the reference standard.

RESULTS

In 72 (13.2%) patients, CT colonography depicted 88 endoscopically nonvisualized lesions 6 mm or greater. Of 11 patients reported to have 12 masses (> or =20 mm), at subsequent colonoscopy, one patient had no mass. Eighteen patients had 23 large (10-19-mm) polyps that they were suspected of having, and 47 patients had 53 medium (6-9-mm) polyps that they were suspected of having. At a median follow-up of 31 months (range, 6-42 months), 45 (63%) of 72 patients underwent follow-up colonoscopy because of their CT colonographic findings. Rates of repeat colonoscopy for masses, large polyps, and medium polyps were 100%, 94%, and 45%, respectively. Per-patient and per-lesion PPVs of CT colonography for masses, large polyps, and medium polyps were 90.9% and 91.7%, 64.7% and 70%, and 33.3% and 30.4%, respectively.

CONCLUSION

CT colonography has the potential to become an accepted technique for evaluation of the nonvisualized part of the colon after incomplete colonoscopy, and it can increase the diagnostic yield of masses and clinically important polyps in this part of the colon.

MR colonography without bowel purgation for the assessment of inflammatory bowel diseases: diagnostic accuracy and patient acceptance

BACKGROUND

The purpose of this pilot study was to assess the diagnostic accuracy of MR colonography (MRC) without bowel cleansing regarding its ability to quantify inflammatory bowel disease (IBD). In addition, patient acceptance was compared with conventional colonoscopy (CC).

METHODS

In all, 29 patients with IBD (17 ulcerative colitis; 12 Crohn's disease) were included. While CC was performed after bowel cleansing as the gold standard, MRC was based on a fecal tagging technique and performed 48-72 hours prior to CC. The presence of inflammation in each of 7 ileocolonic segments was rated for every procedure. Patients evaluated both modalities and dedicated aspects of the examination according to a 10-point-scale (1 = good, 10 = poor acceptance). Furthermore, preferences for future examinations were investigated.

RESULTS

Inflammatory segments were found by means of CC in 23 and by MRC in 14 patients. Overall sensitivity and specificity of MRC in a segment-based detection were 32% and 88%, respectively. Concerning severely inflamed segments, sensitivity increased to 53% for MRC. Overall acceptance of CC was significantly higher compared to MRC (mean value (mv) for MRT = 6.0; CC = 4.1; P = 0.003). For MRC, the placement of the rectal tube (mv = 7.3), and for CC bowel purgation (mv = 6.5), were rated as the most unpleasant. A total of 67% of patients voted for CC as the favorable tool for future examinations.

CONCLUSIONS

The presented data indicate that 'fecal tagging MRC' is not suitable for an adequate quantification of inflammatory diseases of the large bowel. Furthermore, overall acceptance of endoscopic colonoscopy was superior to MRC.

Colonoscopy technique in consecutive patients referred for prior incomplete colonoscopy

BACKGROUND & AIMS

Cecal intubation is one of the goals of colonoscopy. In some patients cecal intubation is unsuccessful. The aim of this study was to describe the approach used by a gastroenterologist with special interest in colonoscopy to perform colonoscopy in patients with a prior incomplete colonoscopy.

METHODS

The demographic features and colonoscopy methods and findings are described in 119 consecutive patients in whom a prior incomplete colonoscopy was performed by a gastroenterologist or surgeon.

RESULTS

Most patients could be characterized as to the cause of previous failure, based on medical records or an initial attempt to pass the colonoscope, as redundant colon (n = 54), difficult sigmoid colon (n = 33), or difficult to sedate (n = 8). Colonoscopy was successful to the cecum (n = 116) or an ileocolonic anastomosis (n = 1) in 117 of the 119 patients. Standard adult (n = 51) and pediatric colonoscopes (n = 35) and attention to careful technique were successful in 86 cases, although these included 7 cases in which the use of propofol sedation appeared to be the critical factor allowing success. Special equipment was needed in 31 cases: external straighteners (n = 9), upper endoscopes alone (n = 9), pediatric colonoscope after guidewire exchange (n = 8), and an enteroscope with (n = 4) or without (n = 1) an external straightener.

CONCLUSIONS

Most patients with a prior incomplete colonoscopy can be colonoscoped successfully if an array of tools and techniques are used. The approach varies depending on characterization of the problem as redundant colon vs difficult sigmoid colon. The approach and techniques described here may be of value to others in cases of a difficult or challenging colonoscopy.

Virtual fly-over: a new visualization technique for virtual colonoscopy

In this paper, we propose a new visualization technique for virtual colonoscopy (VC). The proposed method is called Virtual Fly-Over, which splits the entire colon anatomy into exactly two halves. Then, it assigns a virtual camera to each half to perform fly-over navigation, which has several advantages over both traditional fly-through and related methods. First, by controlling the elevation of the camera, there is no restriction on its field of view (FOV) angle (e.g., >90 degrees) to maximize visualized surface areas, and hence no perspective distortion. Second, the camera viewing volume is perpendicular to each colon half, so potential polyps that are hidden behind haustral folds are easily found. Finally, because the orientation of the splitting surface is controllable, the navigation can be repeated at a different split orientation to overcome the problem of having a polyp that is divided between the two halves of the colon. Quantitative experimental results on 15 clinical datasets have shown that the average surface visibility coverage is 99.59 +/- 0.2%.