CT colonography in 546 patients with incomplete colonoscopy

[CT colonography : Technique and indications]

BACKGROUND

Dedicated radiological expertise and a high-quality examination, performed according to current technical standards and for accepted indications, are prerequisite to achieve excellent results with CT colonography (CTC).

OBJECTIVES

The aim of this article is to review current standards of the examination technique as well as indications and contraindications for CTC based on recent recommendations and guidelines.

MATERIALS AND METHODS

Based on extensive literature research, current knowledge about the examination technique and the indications and contraindications is summarized.

RESULTS

CTC is the radiological examination of choice for the detection of colorectal neoplasia. Beside incomplete or refused colonoscopy and contraindications to colonoscopy, CTC is also a noninvasive option for opportunistic colorectal cancer screening. The examination technique is based on a CTC-specific patient preparation scheme that includes fecal tagging, colonic distension, low-dose CT scans in two patient positions and a combined 2D and 3D data evaluation.

CONCLUSIONS

Performing CTC according to current technical standards is prerequisite for high-quality examinations and is, thus, also a key factor to obtain a correct diagnosis. CTC is a noninvasive examination, capable of providing clinically relevant diagnoses for a wide range of indications.

Intestinal malrotation in adults: prevalence and findings based on CT colonography

OBJECTIVES

Intestinal malrotation is largely a pediatric diagnosis, but initial detection can be made in adulthood. CT colonography (CTC) provides an ideal means for estimating prevalence. Our purpose was to evaluate the prevalence and imaging findings of intestinal malrotation in asymptomatic adults at CTC screening, as well as incomplete optical colonoscopy (OC) referral.

METHODS

The CTC database of a single academic institution was searched for cases of intestinal malrotation (developmental nonrotation). Prevalence was estimated from 11,176 adults undergoing CTC. Demographic, clinical, imaging (CTC and other abdominal exams), and surgical data were reviewed.

RESULTS

27 cases of malrotation were confirmed (mean age 62 ± 9 years; 15 M/12F), including 17 from the CTC screening cohort (0.17% prevalence) and 10 from incomplete OC (0.75% prevalence; p < 0.001). Most cases (59%; 16/27) were initially diagnosed at CTC. In 67% (12/18); the presence of malrotation was missed on at least one relevant abdominal imaging examination. At least 22% (6/27) had a history of unexplained, chronic intermittent abdominal pain. At CTC, the SMA-SMV relationship was normal in only 11% (3/27). The ileocecal valve was located in the RLQ in only 22% (6/27). Two patients (7%) had associated findings of heterotaxy (polysplenia).

CONCLUSIONS

The prevalence of intestinal malrotation was four times greater for patients referred from incomplete OC compared with primary screening CTC, likely related to anatomic challenges at endoscopy. Malrotation was frequently missed at other abdominal imaging examinations. CTC can uncover unexpected cases of malrotation in adults, which may be relevant in terms of potential for future complications.

Computed tomography colonography and radiation risk: How low can we go?

Computed tomography colonography (CTC) has become a key examination in detecting colonic polyps and colorectal carcinoma (CRC). It is particularly useful after incomplete optical colonoscopy (OC) for patients with sedation risks and patients anxious about the risks or potential discomfort associated with OC. CTC's main advantages compared with OC are its non-invasive nature, better patient compliance, and the ability to assess the extracolonic disease. Despite these advantages, ionizing radiation remains the most significant burden of CTC. This opinion review comprehensively addresses the radiation risk of CTC, incorporating imaging technology refinements such as automatic tube current modulation, filtered back projections, lowering the tube voltage, and iterative reconstructions as tools for optimizing low and ultra-low dose protocols of CTC. Future perspectives arise from integrating artificial intelligence in computed tomography machines for the screening of CRC.

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.

Performance of radiographic imaging after incomplete colonoscopy for nonmalignant causes in clinical practice

BACKGROUND AND AIMS

CT colonography (CTC) or barium enema are commonly ordered to complete colorectal imaging after an incomplete colonoscopy. We evaluated the sensitivity of radiographic studies performed for this purpose in clinical practice outside clinical trials.

METHODS

Adult patients referred to an expert endoscopist for incomplete colonoscopy because of a redundant colon or a difficult sigmoid and who underwent previous radiographic imaging between July 2001 and July 2019 were identified. None of the patients had a malignant obstruction as the cause of incomplete colonoscopy. Data on polyp size, location, and pathology were obtained from colonoscopy and radiology reports. Polyps identified on imaging and colonoscopy were matched based on polyp size and location.

RESULTS

Among 769 patients referred for incomplete colonoscopy, we identified 65 with a radiographic examination performed within 36 months of colonoscopy at our center. Per-patient sensitivity for CTC was suboptimal (70%) and was very low for barium enema (26.7%). Per-polyp sensitivity for both CTC and barium enema was poor (23.8% and 7.6%). Quality of the examination did not seem to affect procedure sensitivity.

CONCLUSIONS

Radiographic imaging after incomplete colonoscopy for reasons other than malignant obstruction had poor sensitivity for polyps. Patients with incomplete colonoscopies should be considered for repeat colonoscopy by an expert.

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.

Synchronous colorectal cancer using CT colonography vs. other means: a systematic review and meta-analysis

OBJECTIVES

The objective of our study was to systematically review the evidence about synchronous colorectal cancer diagnosed with or without computed tomography colonography (CTC).

MATERIALS AND METHODS

Two systematic searches were performed (PubMed and EMBASE) for studies reporting the prevalence of synchronous colorectal cancer (CRC): one considering patients who underwent CTC and the another one considering patients who did not undergo CTC. A three-level analysis was performed to determine the prevalence of patients with synchronous CRC in both groups of studies. Heterogeneity was explored for multiple variables. Pooled prevalence and 95% confidence interval (CI) were calculated. A quality assessment (STROBE) was done for the studies.

RESULTS

For CTC studies, among 2645 articles initially found, 21 including 1673 patients, published from 1997 to 2018, met the inclusion criteria. For non-CTC studies, among 6192 articles initially found, 27 including 111,873 patients published from 1974 to 2015 met the inclusion criteria. The pooled synchronous CRC prevalence was 5.7% (95% CI 4.7%-7.1%) for CTC studies, and 3.9% (95% CI 3.3%-4.4%) for non-CTC studies, with a significant difference (p = 0.004). A low heterogeneity was found for the CTC group (I² = 10.3%), whereas a high heterogeneity was found in the non-CTC group of studies (I² = 93.5%), and no significant explanatory variables were found. Of the 22 STROBE items, a mean of 18 (82%) was fulfilled by CTC studies, and a mean of 16 (73%) by non-CTC studies.

CONCLUSIONS

The prevalence of synchronous CRC was about 4-6%. The introduction of CTC is associated with a significant increase of the prevalence of synchronous CRCs.

The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Treatment of Colon Cancer

The American Society of Colon and Rectal Surgeons is dedicated to ensuring high-quality patient care by advancing the science, prevention, and management of disorders and diseases of the colon, rectum, and anus. The Clinical Practice Guidelines Committee is composed of society members who are chosen because they have demonstrated expertise in the specialty of colon and rectal surgery. This committee was created to lead international efforts in defining quality care for conditions related to the colon, rectum, and anus. This is accompanied by developing Clinical Practice Guidelines based on the best available evidence. These guidelines are inclusive and not prescriptive. Their purpose is to provide information on which decisions can be made, rather than to dictate a specific form of treatment. These guidelines are intended for the use of all practitioners, health care workers, and patients who desire information about the management of the conditions addressed by the topics covered in these guidelines. It should be recognized that these guidelines should not be deemed inclusive of all proper methods of care or exclusive of methods of care reasonably directed to obtaining the same results. The ultimate judgment regarding the propriety of any specific procedure must be made by the physician in light of all the circumstances presented by the individual patient.

Development and validation of an algorithm to complete colonoscopy using standard endoscopes in patients with prior incomplete colonoscopy

BACKGROUND AND STUDY AIMS

 Incomplete colonoscopy may occur as a result of colon angulation (adhesions or diverticulosis), endoscope looping, or both. Specialty endoscopes/devices have been shown to successfully complete prior incomplete colonoscopies, but may not be widely available. Radiographic or other image-based evaluations have been shown to be effective but may miss small or flat lesions, and colonoscopy is often still indicated if a large lesion is identified. The purpose of this study was to develop and validate an algorithm to determine the optimum endoscope to ensure completion of the examination in patients with prior incomplete colonoscopy.

PATIENTS AND METHODS

 This was a prospective cohort study of 175 patients with prior incomplete colonoscopy who were referred to a single endoscopist at a single academic medical center over a 3-year period from 2012 through 2015. Colonoscopy outcomes from the initial 50 patients were used to develop an algorithm to determine the optimal standard endoscope and technique to achieve cecal intubation. The algorithm was validated on the subsequent 125 patients.

RESULTS

 The overall repeat colonoscopy success rate using a standard endoscope was 94 %. The initial standard endoscope specified by the algorithm was used and completed the colonoscopy in 90 % of patients.

CONCLUSIONS

 This study identifies an effective strategy for completing colonoscopy in patients with prior incomplete examination, using widely available standard endoscopes and an algorithm based on patient characteristics and reasons for prior incomplete colonoscopy.

Retrospective analysis of computed tomographic colonography in a rural hospital

INTRODUCTION

The aims of this study were to investigate the diagnostic performance of computed tomography colonography (CTC) performed in a rural secondary hospital, and to describe the local pattern of CTC service provision.

METHOD

A single site, retrospective observational analysis was conducted for all patients undergoing CTC during the 12-month period from 1st of January to 31st of December 2014 with comparison to available colonoscopy.

RESULTS

There were 639 CTCs performed during the 12-months period. The average time from referral to performance of CTC scan was 21.3 days. The diagnostic yield of CTC for CRC was 5.8%; and for large polyps ≥10 mm was 8.0%. The sensitivity and specificity of CTC for detecting CRC were 97.1% and 88.2% respectively. The most predictive symptoms for finding colorectal lesions were rectal bleeding and anaemia. The referral rate from CTC to colonoscopy was 16.9%. 63 patients (9.9%) had follow up recommendations made in their reports due to extracolonic findings.

CONCLUSION

Computed tomography colonography performed in a rural secondary hospital provided sufficient sensitivity to detect large polyps or CRC. The specificity for CRC was lower than reported figures in the literature. Technical issue of CTC performance due to poor insufflation techniques was identified as a main contributing factor reducing CTC accuracy. CTCs were performed with acceptable waiting time and showed high overall diagnostic yield for colorectal neoplasm in a rural hospital.

Alternatives to Incomplete Colonoscopy

A thorough and complete colonoscopy is critically important in preventing colorectal cancer. Factors associated with difficult and incomplete colonoscopy include a poor bowel preparation, severe diverticulosis, redundant colon, looping, adhesions, young and female patients, patient discomfort, and the expertise of the endoscopist. For difficult colonoscopy, focusing on bowel preparation techniques, appropriate sedation and adjunct techniques such as water immersion, abdominal pressure techniques, and patient positioning can overcome many of these challenges. Occasionally, these fail and other alternatives to incomplete colonoscopy have to be considered. If patients have low risk of polyps, then noninvasive imaging options such as computed tomography (CT) or magnetic resonance (MR) colonography can be considered. Novel applications such as Colon Capsule™ and Check-Cap are also emerging. In patients in whom a clinically significant lesion is noted on a noninvasive imaging test or if they are at a higher risk of having polyps, balloon-assisted colonoscopy can be performed with either a single- or double-balloon enteroscope or colonoscope. The application of these techniques enables complete colonoscopic examination in the vast majority of patients.

Symptomatic Versus Asymptomatic Colorectal Cancer: Predictive Features at CT Colonography

RATIONALE AND OBJECTIVES

Computed tomographic colonography (CTC) is a robust tool for evaluating colorectal lesions in both screening and diagnostic settings. The purpose of this study was to assess the relationship between colorectal cancer (CRC) tumor characteristics and patient symptomatology.

MATERIALS AND METHODS

This is a retrospective analysis of all pathology-confirmed cases of CRC evaluated with CTC at our institution from October 2004 to October 2012. Cases were reviewed to determine tumor size, morphology, and degree of luminal narrowing. An electronic medical record review was performed to delineate specific patient symptomatology and determine depth of invasion.

RESULTS

A total of 55 patients (36 symptomatic and 19 asymptomatic) with a total of 63 CRCs were evaluated by CTC during the study time period. The most common symptoms were gastrointestinal (GI) bleeding/anemia (n = 26), followed by obstructive symptoms (n = 23), and constitutional symptoms (n = 5). Symptomatic cancers were more likely to have annular morphology (n = 30/43, 70% vs. n = 3/20, 15%; odds ratio [OR] = 13.1, P = 0.0003), whereas asymptomatic cancers were more likely to be polypoid (n = 11/20, 55% vs. n = 6/43, 14%, OR = 7.5, P = 0.001). Symptomatic cancers were also larger (46.1 ± 22.4 vs. 38.8 ± 18.4 mm, P = 0.005) and resulted in greater luminal narrowing (8.7 ± 8.5 mm vs. 35.8 ± 18.8 mm, P < 0.0001) with deeper invasion (n = 29/35 [invasion unknown for 8 cases], 83% vs. n = 6/20, 30%, OR = 11.3, P = 0.0003). Invasive cancers were more likely to have annular morphology (66%, 23/25, P = 0.002).

CONCLUSIONS

There is an intuitive and predictable relationship between tumor characteristics on CTC and patient symptoms. Annular morphology, tumor size, degree of luminal narrowing, and invasive disease all correlate with the presence of symptoms.

Diagnostic value of computed tomography colonography (CTC) after incomplete optical colonoscopy

INTRODUCTION

This study evaluated the role of computed tomography colonography (CTC) in patients who previously underwent incomplete optical colonoscopy (OC). We analyzed the impact of colonic lesions in intestinal segments not studied by OC and extracolonic findings in these patients.

METHODS

Between January 2014 and May 2015, 61 patients with a history of abdominal pain and incomplete OC examination were studied by CTC. CTCs were performed by 320-row CT scan in both the supine and the prone position, without intravenous administration of contrast medium. In all patients both colonic findings and extracolonic findings were evaluated.

RESULTS

Among the study group, 24 CTC examinations were negative for both colonic and extracolonic findings while 6 examinations revealed the presence of both colonic and extracolonic findings. In 24 patients CTC depicted colonic anomalies without extracolonic ones, while in 7 patients it showed extracolonic findings without colonic ones.

DISCUSSION

CTC is a noninvasive imaging technique with the advantages of high diagnostic performance, rapid data acquisition, minimal patient discomfort, lack of need for sedation, and virtually no recovery time. CTC accurately allows the evaluation of the nonvisualized part of the colon after incomplete OC and has the distinct advantage to detect clinically important extracolonic findings in patients with incomplete OC potentially explaining the patient's symptoms and conditioning their therapeutic management.

CONCLUSION

CTC accurately allows the assessment of both colonic and extracolonic pathologies representing a useful diagnostic tool in patients for whom complete OC is not achievable.

Computed tomography colonography for the practicing radiologist: A review of current recommendations on methodology and clinical indications

Colorectal cancer (CRC) represents one of the most relevant causes of morbidity and mortality in Western societies. CRC screening is actually based on faecal occult blood testing, and optical colonoscopy still remains the gold standard screening test for cancer detection. However, computed tomography colonography (CT colonography) constitutes a reliable, minimally-invasive method to rapidly and effectively evaluate the entire colon for clinically relevant lesions. Furthermore, even if the benefits of its employment in CRC mass screening have not fully established yet, CT colonography may represent a reasonable alternative screening test in patients who cannot undergo or refuse colonoscopy. Therefore, the purpose of our review is to illustrate the most updated recommendations on methodology and the current clinical indications of CT colonography, according to the data of the existing relevant literature.

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.

Predictors of incomplete optical colonoscopy using computed tomographic colonography

BACKGROUND/AIMS

Optical colonoscopy (OC) is the primary modality for investigation of colonic pathology. Although there is data on demographic factors for incomplete OC, paucity of data exists for anatomic variables that are associated with an incomplete OC. These anatomic variables can be visualized using computed tomographic colonography (CTC). We aim to retrospectively identify variables associated with incomplete OC using CTC and develop a scoring method to predict the outcome of OC.

PATIENTS AND METHODS

In this case-control study, 70 cases ( with incomplete OC) and 70 controls (with complete OC) were identified. CTC images of cases and controls were independently reviewed by a single CTC radiologist. Demographic and anatomical parameters were recorded. Data was examined using descriptive linear statistics and multivariate logistic regression model.

RESULTS

On analysis, female gender (80% vs 58.6% P = 0.007), prior abdominal/pelvic surgeries (51.4% vs 14.3% P < 0.001), colonic length (187.6 ± 30.0 cm vs 163.8 ± 27.2 cm P < 0.001), and number of flexures (11.4 ± 3.1 vs 8.4 ± 2.9 P < 0.001) increased the risk for incomplete OC. No significant association was observed for increasing age (P = 0.881) and history of severe diverticulosis (P = 0.867) with incomplete OC. A scoring system to predict the outcome of OC is proposed based on CTC findings.

CONCLUSION

Female gender, prior surgery, and increasing colonic length and tortuosity were associated with incomplete OC, whereas increasing age and history of severe diverticulosis were not. These factors may be used in the future to predict those patients who are at risk of incomplete OC.

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.

Colon capsule versus CT colonography in patients with incomplete colonoscopy: a prospective, comparative trial

OBJECTIVE

In case of incomplete colonoscopy, several radiologic methods have traditionally been used, but more recently, capsule endoscopy was also shown to be accurate. Aim of this study was to compare colon capsule endoscopy (CCE) and CT colonography (CTC) in a prospective cohort of patients with incomplete colonoscopy.

DESIGN

Consecutive patients with a previous incomplete colonoscopy underwent CCE and CTC followed by colonoscopy in case of positive findings on either test (polyps/mass lesions ≥6 mm). Clinical follow-up was performed in the other cases to rule out missed cancer. CTC was performed after colon capsule excretion or 10-12 h postingestion. Since the gold standard colonoscopy was performed only in positive cases, diagnostic yield and positive predictive values of CCE and CTC were used as study end-points.

RESULTS

100 patients were enrolled. CCE and CTC were able to achieve complete colonic evaluation in 98% of cases. In a per-patient analysis for polyps ≥6 mm, CCE detected 24 patients (24.5%) and CTC 12 patients (12.2%). The relative sensitivity of CCE compared to CTC was 2.0 (95% CI 1.34 to 2.98), indicating a significant increase in sensitivity for lesions ≥6 mm. Of larger polyps (≥10 mm), these values were 5.1% for CCE and 3.1% for CTC (relative sensitivity: 1.67 (95% CI 0.69 to 4.00)). Positive predictive values for polyps ≥6 mm and ≥10 mm were 96% and 85.7%, and 83.3% and 100% for CCE and CTC, respectively. No missed cancer occurred at clinical follow-up of a mean of 20 months.

CONCLUSIONS

CCE and CTC were of comparable efficacy in completing colon evaluation after incomplete colonoscopy; the overall diagnostic yield of colon capsule was superior to CTC.

TRIAL REGISTRATION NUMBER

NCT01525940.

CT colonography for evaluation of colorectal cancer

AIM: To evaluate the value of computed tomography colonography (CTC) in the evaluation of colorectal cancer by comparing its performance with colonoscopy.

METHODS: Forty-one patients who were diagnosed with colorectal cancer by colonoscopic biopsy and underwent CTC and colonoscopy were included in the study. CTC and colonoscopy were compared for their performance in the evaluation of colorectal cancer.

RESULTS: The locations of tumors revealed by CTC and colonoscopy were consistent. However, colonoscopy had its limitation in determining the size of the tumor, and tumor size was measured by colonoscopy in 54% (23/43) of cases , in contrast to 95% (41/43) of cases by CTC. There was no statistical significance in the pathological type revealed by the two techniques (P = 0.621). Colonoscopy failed to evaluate the condition outside the intestinal tract and the proximal colon in cases with colon obstruction, resulting in incomplete examination. The grade of subjective tolerability was significantly lower for colonoscopy than for CTC (P = 0.000).

CONCLUSION: CTC can evaluate colorectal cancer effectively, although it cannot replace colonoscopy entirely. CTC can be chosen as a preferred means for patients who cannot tolerate colonoscopy as well as patients who have incomplete colonoscopy examination.

ACR Appropriateness Criteria colorectal cancer screening

Colorectal cancer is the third leading cause of cancer deaths in the United States. Most colorectal cancers can be prevented by detecting and removing the precursor adenomatous polyp. Individual risk factors for the development of colorectal cancer will influence the particular choice of screening tool. CT colonography (CTC) is the primary imaging test for colorectal cancer screening in average-risk individuals, whereas the double-contrast barium enema (DCBE) is now considered to be a test that may be appropriate, particularly in settings where CTC is unavailable. Single-contrast barium enema has a lower performance profile and is indicated for screening only when CTC and DCBE are not available. CTC is also the preferred test for colon evaluation following an incomplete colonoscopy. Imaging tests including CTC and DCBE are not indicated for colorectal cancer screening in high-risk patients with polyposis syndromes or inflammatory bowel disease. This paper presents the updated colorectal cancer imaging test ratings and is the result of evidence-based consensus by the ACR Appropriateness Criteria Expert Panel on Gastrointestinal Imaging. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

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.

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.

[CT colonography as routine method]

CLINICAL/METHODICAL ISSUE

Colorectal cancer is a major public health challenge in Austria and Germany. As the participation in dedicated colonoscopy screening programs is rather low, the question of alternative methods is raised again and computed tomography (CT) colonography seems to be a gentle alternative with a very high patient acceptance.

STANDARD RADIOLOGICAL METHODS

In recent years CT colonography (CTC) has been established besides conventional colonoscopy as a radiological method for the investigation of the entire colon. From axial two-dimensional images three-dimensional images can be generated, allowing a virtual flight through the colon which is why this technique is also known as virtual colonoscopy.

METHODICAL INNOVATIONS

The technique of CTC has been improved continuously during recent years. On the one hand the steady decrease in the layer thickness (currently ≤ 1 mm) has improved the resolution of volume data sets and on the other hand there has been significant progress in postprocessing.

PERFORMANCE

Numerous studies have recently shown that the significance of CTC in the detection of advanced adenomas is similar to conventional colonoscopy.

ACHIEVEMENTS

Meanwhile CT colonography is now a routine investigation method established in both symptomatic and asymptomatic patients (screening).

PRACTICAL RECOMMENDATIONS

Study data now clearly show that CTC, as an alternative to conventional colonoscopy, is a powerful method for investigation of colorectal cancer. To achieve good results adequate preparation including fecal tagging, standardized technical procedures during the investigation and expertise in both 2D and 3D reading are essential.

Current status on performance of CT colonography and clinical indications

CT colonography (CTC) is a robust and reliable imaging test of the colon. Accuracy for the detection of colorectal cancer (CRC) is as high as conventional colonoscopy (CC). Identification of polyp is size dependent, with large lesions (≥10mm) accurately detected and small lesions (6-9mm) identified with moderate to good sensitivity. Recent studies show good sensitivity for the identification of nonpolypoid (flat) lesions as well. Current CTC indications include the evaluation of patients who had undergone a previous incomplete CC or those who are unfit for CC (elderly and frail individuals, patients with underlying severe clinical conditions, or with contraindication to sedation). CTC can also be efficiently used in the assessment of diverticular disease (excluding patients with acute diverticulitis, where the exam should be postponed), before laparoscopic surgery for CRC (to have an accurate localization of the lesion), in the evaluation of colonic involvement in the case of deep pelvic endometriosis (replacing barium enema). CTC is also a safe procedure in patients with colostomy. For CRC screening, CTC should be considered an opportunistic screening test (not available for population, or mass screening) to be offered to asymptomatic average-risk individuals, of both genders, starting at age 50. The use in individuals with positive family history should be discussed with the patient first. Absolute contraindication is to propose CTC for surveillance of genetic syndromes and chronic inflammatory bowel diseases (in particular, ulcerative colitis). The use of CTC in the follow-up after surgery for CRC is achieving interesting evidences despite the fact that literature data are still relatively weak in terms of numerosity of the studied populations. In patients who underwent previous polypectomy CTC cannot be recommended as first test because debate is still open. It is desirable that in the future CTC would be the first-line and only diagnostic test for colonic diseases, leaving to CC only a therapeutic role.

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.

Recommendations and expert opinion on the treatment of locally advanced rectal cancer in Spain

In Spain 22,000 new cases of colorectal cancer are diagnosed each year, with 13,075 deaths resulting from this disease. Around 70% of colorectal cancers are localised in the colon and 30% in the rectum. A group of Spanish experts established recommendations on what would be the best strategy in the treatment of locally advanced rectal cancer (LARC). Adequate assessment of local tumour extension, including high-resolution magnetic resonance imaging and endorectal ultrasound, is essential for successful treatment. The three cornerstones in the treatment of LARC are surgery, radiotherapy and chemotherapy. Most patients will need a total mesorectal excision (TME). Preoperative chemo-radiotherapy (CRT) is preferred for the majority of patients with T3/T4 disease and/or regional node involvement, and adjuvant chemotherapy is recommended after a patient-sharing decision. Capecitabine, after showing a trend in improved downstaging in neoadjuvant stratum and the convenience of its oral administration, represents an alternative to 5-FU as perioperative treatment of LARC.

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.

Laparoscopic extraperitoneal rectal cancer surgery: the clinical practice guidelines of the European Association for Endoscopic Surgery (EAES)

BACKGROUND

The laparoscopic approach is increasingly applied in colorectal surgery. Although laparoscopic surgery in colon cancer has been proved to be safe and feasible with equivalent long-term oncological outcome compared to open surgery, safety and long-term oncological outcome of laparoscopic surgery for rectal cancer remain controversial. Laparoscopic rectal cancer surgery might be efficacious, but indications and limitations are not clearly defined. Therefore, the European Association for Endoscopic Surgery (EAES) has developed this clinical practice guideline.

METHODS

An international expert panel was invited to appraise the current literature and to develop evidence-based recommendations. The expert panel constituted for a consensus development conference in May 2010. Thereafter, the recommendations were presented at the annual congress of the EAES in Geneva in June 2010 in a plenary session. A second consensus process (Delphi process) of the recommendations with the explanatory text was necessary due to the changes after the consensus conference.

RESULTS

Laparoscopic surgery for extraperitoneal (mid- and low-) rectal cancer is feasible and widely accepted. The laparoscopic approach must offer the same quality of surgical specimen as in open surgery. Short-term outcomes such as bowel function, surgical-site infections, pain and hospital stay are slightly improved with the laparoscopic approach. Laparoscopic resection of rectal cancer is not inferior to the open in terms of disease-free survival, overall survival or local recurrence. Laparoscopic pelvic dissection may impair genitourinary and sexual function after rectal resection, like in open surgery.

CONCLUSIONS

Laparoscopic surgery for mid- and low-rectal cancer can be recommended under optimal conditions. Still, most level 1 evidence is for colon cancer surgery rather than rectal cancer. Upcoming results from large randomised trials are awaited to strengthen the evidence for improved short-term results and equal long-term results in comparison with the open approach.

Computed tomographic colonography in preoperative evaluation of colorectal tumors: a prospective study

Background

This study aimed to assess the usefulness of computed tomographic colonography (CTC) in preoperative evaluation of colorectal tumors and the entire bowel including endoscopically inaccessible regions.

Methods

Colonoscopy and CTC were performed for 49 patients. The tumor and the entire colon were assessed, and the results were compared with colonoscopy. The extraluminal findings of CTC were compared with contrast-enhanced computed tomography (CT) of the abdomen and the pelvis in 33 patients. All these patients had undergone surgery. A comparison of results for tumor node metastasis classification between CTC, CT, and histopathology was performed.

Results

Exploration of the entire colon was possible for 89.8% of the patients using CTC and 49.0% of the patients using colonoscopy. Bowel cleansing was assessed as worse with CTC. In the evaluation of tumor location and morphologic type, CTC was congruent with colonoscopy. Colonoscopy enabled approximate tumor size and volume to be evaluated for only 59.2% (29/49) and 30.6% (15/49) of patients, respectively, whereas CTC enabled evaluation of all 48 (100.0%) visualized tumors. Wall thickening, outer contour, and suspected infiltration of surrounding tissues and organs are impossible to determine with colonoscopy but can be determined with CTC. Using CTC, two additional tumors were found proximate to occlusive masses in endoscopically inaccessible regions.

Conclusion

Computed tomographic colonography is a useful method for diagnosing colorectal tumors. It allows the clinician to diagnose tumor, determine local tumor progression, and detect synchronous lesions in the large bowel including endoscopically inaccessible regions.

CT colonography for postoperative surveillance after curative gastrectomy in patients with gastric cancer

AIM

The purpose was to evaluate the diagnostic role of contrast-enhanced CT colonography (CTC) for follow-up of colorectal cancer screening after curative gastrectomy in patients with gastric adenocarcinomas.

MATERIALS AND METHODS

Contrast-enhanced CTC was performed as a substitute for routine follow-up CT for the detection of recurrent lesions in 700 consecutive patients who underwent curative surgery for gastric adenocarcinomas. Prospectively, patients with polyps measuring 6 mm or larger on CTC were referred for optical colonoscopy. Clinical and radiologic follow-up with respect to detection of polyp and recurrent lesion was retrospectively assessed.

RESULTS

Colorectal polyps measuring 6 mm or larger were identified by CTC in 104 (14.9%) of the 700 patients. Optical colonoscopy was recommended to these patients and was performed in 72 cases. True positive lesions were identified in 62 of the 72 patients (per-patient positive predictive value: 86.1%). The diagnostic yield for primary colonic malignancies was 1.6% (11/700). Recurrent lesions of gastric cancer were also detected in eight patients (1.1%).

CONCLUSION

In patients who undergo gastrectomy due to gastric adenocarcinoma, contrast-enhanced CTC may offer a unique advantage by allowing simultaneous colorectal cancer screening in addition to its routine role of detecting recurrent lesions during follow-up.

Should barium enema be the next step following an incomplete colonoscopy?

INTRODUCTION

Double contrast barium enema (DCBE) is used to screen and diagnose colorectal disease and is often recommended following an incomplete colonoscopy. The purpose of this study was to determine the value of DCBE following an incomplete colonoscopy.

MATERIALS AND METHODS

A retrospective review was conducted of all patients who had an incomplete colonoscopy at Kaiser Permanente, Los Angeles in a 6-year period. Patient data was extracted from the endoscopy and radiology databases. Variables collected included demographics, indication for colonoscopy, reason for incompletion, findings of DCBE, and findings of repeat colonoscopy if subsequently performed.

RESULTS

The incomplete colonoscopy rate was 1.6%. The mean age was 62 years with a predominance of females. The most common indication for colonoscopy was screening. The most frequent reason attributed to an incomplete colonoscopy was patient discomfort. Two hundred thirty three patients underwent DCBE and 42 patients underwent a repeat colonoscopy without DCBE; 13.3% of the DCBE were of poor quality and could not be interpreted. A repeat colonoscopy following DCBE was performed in 7% of patients. In 50% of these patients, the repeat colonoscopy revealed significant findings not noted on the DCBE or ruled out positive DCBE findings. In patients who had repeat colonoscopy without DCBE, completion rate was 95%.

CONCLUSION

The rate of incomplete colonoscopy in a high-volume modern endoscopy unit is extremely low. DCBE following incomplete colonoscopy has limited value. A repeat colonoscopy under deeper sedation and/or better bowel preparation may be the preferred next step.

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.

Colorectal cancer

Substantial progress has been made in colorectal cancer in the past decade. Screening, used to identify individuals at an early stage, has improved outcome. There is greater understanding of the genetic basis of inherited colorectal cancer and identification of patients at risk. Optimisation of surgery for patients with localised disease has had a major effect on survival at 5 years and 10 years. For rectal cancer, identification of patients at greatest risk of local failure is important in the selection of patients for preoperative chemoradiation, a strategy proven to improve outcomes in these patients. Stringent postoperative follow-up helps the early identification of potentially radically treatable oligometastatic disease and improves long-term survival. Treatment with adjuvant fluoropyrimidine for colon and rectal cancers further improves survival, more so in stage III than in stage II disease, and oxaliplatin-based combination chemotherapy is now routinely used for stage III disease, although efficacy must be carefully balanced against toxicity. In stage II disease, molecular markers such as microsatellite instability might help select patients for treatment. The integration of targeted treatments with conventional cytotoxic drugs has expanded the treatment of metastatic disease resulting in incremental survival gains. However, biomarker development is essential to aid selection of patients likely to respond to therapy, thereby rationalising treatments and improving outcomes.

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.

Quality initiatives: quality improvement grand rounds at Beth Israel Deaconess Medical Center: CT colonography performance review after an adverse event

As computed tomographic (CT) colonography is being used increasingly in clinical practice, an effective quality improvement process must be ensured. The quality improvement process is outlined for the reader by using an adverse event during CT colonography as an example. Components of this process are the approach to a sentinel event, performance of a root cause analysis, and development of strategies for minimizing errors after a serious adverse event. Important factors include indications and contraindications for the examination, proper imaging technique, training of personnel, complications of the procedure, and legal implications. Complications from CT colonography are rare. Attention must be paid to the correct technique for colonic insufflation, particularly in older patients and those who are symptomatic. Root cause analysis provides valuable tools for identification and implementation of improvements designed to avoid similar and other adverse events and to minimize damage.

Virtual colonoscopy in stenosing colorectal cancer

BACKGROUND

Between 5 and 10% of the patients undergoing a colonoscopy cannot have a complete procedure mainly due to stenosing neoplastic lesion of rectum or distal colon. Nevertheless the elective surgical treatment concerning the stenosis is to be performed after the pre-operative assessment of the colonic segments upstream the cancer. The aim of this study is to illustrate our experience with the Computed Tomographic Colonography (CTC) for the pre-operative assessment of the entire colon in the patients with stenosing colorectal cancers.

METHODS

From January 2005 till March 2009, we observed and treated surgically 43 patients with stenosing colorectal neoplastic lesions. All patients did not tolerate the pre-operative colonoscopy. For this reason they underwent a pre-operative CTC in order to have a complete assessment of the entire colon. All patients underwent a follow-up colonoscopy 3 months after the surgical treatment. The CTC results were compared with both macroscopic examination of the specimen and the follow-up coloscopy.

RESULTS

The pre-operative CTC showed four synchronous lesions in four patients (9.3% of the cases). The macroscopic examination of the specimen revealed three small sessile polyps (3-4 mm in diameter) missed in the pre-operative assessment near the stenosing colorectal cancer. The follow-up colonoscopy showed four additional sessile polyps with a diameter between 3-11 mm in three patients. Our experience shows that CTC has a sensitivity of 83,7%.

CONCLUSION

In patients with stenosing colonic lesions, CTC allows to assess the entire colon pre-operatively avoiding the need of an intraoperative colonoscopy. More synchronous lesions are detected and treated at the time of the elective surgery for the stenosing cancer avoiding further surgery later on.

Automated detection and segmentation of large lesions in CT colonography

Computerized tomographic colonography is a minimally invasive technique for the detection of colorectal polyps and carcinoma. Computer-aided diagnosis (CAD) schemes are designed to help radiologists locating colorectal lesions in an efficient and accurate manner. Large lesions are often initially detected as multiple small objects, due to which such lesions may be missed or misclassified by CAD systems. We propose a novel method for automated detection and segmentation of all large lesions, i.e., large polyps as well as carcinoma. Our detection algorithm is incorporated in a classical CAD system. Candidate detection comprises preselection based on a local measure for protrusion and clustering based on geodesic distance. The generated clusters are further segmented and analyzed. The segmentation algorithm is a thresholding operation in which the threshold is adaptively selected. The segmentation provides a size measurement that is used to compute the likelihood of a cluster to be a large lesion. The large lesion detection algorithm was evaluated on data from 35 patients having 41 large lesions (19 of which malignant) confirmed by optical colonoscopy. At five false positive (FP) per scan, the classical system achieved a sensitivity of 78%, while the system augmented with the large lesion detector achieved 83% sensitivity. For malignant lesions, the performance at five FP/scan was increased from 79% to 95%. The good results on malignant lesions demonstrate that the proposed algorithm may provide relevant additional information for the clinical decision process.

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.

Comparison of CT colonography vs. conventional colonoscopy in mapping the segmental location of colon cancer before surgery

Once presence of a colorectal cancer has been diagnosed, a key factor for patient's prognosis in view of surgical intervention is the correct segmental localization and resection of the tumor. The aim of this work was to compare the accuracy of the current gold standard technique, conventional colonoscopy (CC), to computed tomography colonography (CTC) in the segmental localization of tumor. Sixty-five patients (mean age 64; 45 female and 19 male) with colorectal cancer diagnosed at colonoscopy underwent CTC before surgery. In 45 out of 65 cases (69%), patients were referred to CTC after incomplete CC. Reasons were patient intolerance to CC or presence of stenosing cancer, with consistent difficulties in crossing the tract of the colon involved by the lesion. CTC allowed the complete colonic examination in 63/65 cases, since in 2 patients with an obstructing lesion of the sigmoid colon, pneumocolon could not be obtained. However, per patient and per lesion sensitivity of CTC was 100%. Difference from colonoscopy was statistically significant (P < 0.05). In terms of segmental localization of masses, CTC located precisely all lesions, while colonoscopy failed in 16/67 (24%) lesions, though six were missed for incomplete colonoscopy (9%). In the remaining 10/67 (15%) lesions, detected by colonoscopy but incorrectly located, the mismatch occurred in the rectum (n = 3), sigmoid (n = 2), descending (n = 1), transverse (n = 2), ascending colon, and cecum. Agreement between CTC and CC was fair (k value 0.62). Sensitivity, specificity, positive predictive value and negative predictive value of CTC in determining the precise location of colonic masses were respectively 100%, 96%, 85%, and 100%. CT detected hepatic (6/65 patients) and lung metastases (3/65 patients). CT colonography has better performance in the identification of colonic masses (diameter > 3 cm), in the completion of colonic evaluation and in the segmental localization of tumor. CTC should replace colonoscopy for preoperative staging of colorectal cancer.

Diagnostic accuracy of CT colonography and optical colonoscopy evaluated using surgically resected specimens

OBJECTIVE

The aim of this study was to clarify the diagnostic ability of CT colonography (CTC) using surgically resected specimens to avoid inaccuracy associated with optical colonoscopy (OC).

SUBJECTS AND METHODS

CTC and OC were performed in 152 consecutive patients with colorectal cancer. Forty patients had simultaneous lesions other than the ones for which the surgery was intended, and these lesions were used as the gold standard. In 24 patients without stenosis, the sensitivity and positive predictive values (PPV) of CTC and OC were evaluated. In 16 patients with stenosis, the diagnostic ability of CTC for lesions located proximal to the stenosis was assessed.

RESULTS

Sensitivity of CTC and OC was 81% and 66% (P = 0.16), and PPV was 90% and 100% (P = 0.13), respectively. For 22 lesions larger than 5 mm, the sensitivity of CTC and OCS was 96% and 91% (P > 0.50), and PPV was 100% and 100%, respectively. In patients with stenosis, sensitivity and PPV were 89% and 80%, respectively. These results were not significantly different from those in patients without stenosis.

CONCLUSIONS

CTC is a reliable modality for the diagnosis of colorectal polyps. It is also useful to evaluate the colon proximal to severe stenosis which could not be observed by OC.

CT colonography versus optical colonoscopy for screening asymptomatic patients for colorectal cancer a patient, intervention, comparison, outcome (PICO) analysis

RATIONALE AND OBJECTIVES

The American College of Radiology has recently endorsed the use of computed tomographic colonography (CTC) for colon cancer screening. With advances in technology and postprocessing software, the quality of computed tomographic colonographic studies has improved, and new techniques are being developed to reduce radiation exposure and increase patient acceptance of the procedure. The aim of colorectal cancer screening is to reduce the incidence of malignancy by identifying and removing presymptomatic lesions. The aim of this study was to answer the clinical question: In an asymptomatic patient at average risk for colon cancer, is CTC equivalent to optical colonoscopy (OC) for detecting clinically significant polyps?

MATERIALS AND METHODS

A systematic literature review was conducted to evaluate CTC compared to OC, using the patient, intervention, comparison intervention, outcome (PICO) search strategy. The PubMed search used Medical Subject Headings, including the terms "computed tomography colonography," "colonoscopy," "screening," and "polyp." Each of the retrieved articles was assigned a level of evidence using the Centre for Evidence-Based Medicine's hierarchy of validity for diagnostic studies.

RESULTS

PICO search criteria and review of abstracts identified 16 relevant studies. Using the Centre for Evidence-Based Medicine's hierarchy of validity, there were three level 1c studies, two level 2a studies, three level 2b studies, four level 3b studies, two level 4 studies, and two level 5 studies. All relevant studies demonstrated that CTC had high or moderately high per patient and per polyp sensitivity and specificity compared to OC for clinically relevant polyps (>5 mm).

CONCLUSIONS

The majority of evidence suggests that CTC is an acceptable alternative to OC, particularly in the group of patients who are either unwilling or unable to undergo OC. The results of the large, multicenter American College of Radiology Imaging Network study are pending. This trial presented preliminary results in 2007 suggesting that the sensitivity and specificity of CTC are high and comparable to those of OC.