Occlusive colon carcinoma: virtual colonoscopy in the preoperative evaluation of the proximal colon

Colon cancer: the 2023 Korean clinical practice guidelines for diagnosis and treatment

Colorectal cancer is the third most common cancer in Korea and the third leading cause of death from cancer. Treatment outcomes for colon cancer are steadily improving due to national health screening programs with advances in diagnostic methods, surgical techniques, and therapeutic agents.. The Korea Colon Cancer Multidisciplinary (KCCM) Committee intends to provide professionals who treat colon cancer with the most up-to-date, evidence-based practice guidelines to improve outcomes and help them make decisions that reflect their patients' values and preferences. These guidelines have been established by consensus reached by the KCCM Guideline Committee based on a systematic literature review and evidence synthesis and by considering the national health insurance system in real clinical practice settings. Each recommendation is presented with a recommendation strength and level of evidence based on the consensus of the committee.

Ultrathin colonoscopy can improve complete preoperative colonoscopy for stenotic colorectal cancer: Prospective observational study

OBJECTIVES

Preoperative colonoscopy is often incomplete for stenotic colorectal cancers (CRC). This prospective observational study aimed to evaluate the ability of an ultrathin colonoscope (UTC) to inspect the whole colon by passing through the stenotic CRC.

METHODS

All patients who underwent preoperative colonoscopy for stenotic CRCs at Shizuoka Cancer Center were examined for eligibility. If a standard colonoscope (PCF-H290ZI) could not pass because of a stenosis, the patients were recruited. All of the eligible patients were prospectively enrolled when informed consent could be obtained, and complete colonoscopy was attempted again using an UTC (PCF-PQ260L). Patients with stent placement and those requiring right hemicolectomy were not recruited. Primary endpoints were pass-through and cecal intubation rates. The detected synchronous neoplasias (adenomas and cancers) and their pathological findings after resection were evaluated.

RESULTS

A total of 100 patients were enrolled between September 2017 and February 2019. The mean age was 65.6 ± 10.8 years, and 59% were male. The pass-through and cecal intubation rates were 67% (67/100) and 58% (58/100), respectively. Synchronous lesions located proximal to the stenoses were detected in 65.5% (38/58) of the complete colonoscopies, with a total of 86 lesions, including 18 advanced neoplasias with three invasive cancers.

CONCLUSION

When standard colonoscopy cannot pass through stenotic CRC, ultrathin colonoscopy can be considered as an option to inspect the whole colon proximal to the stenosis because treatment strategy can potentially be changed by detecting synchronous neoplasias proximal to the stenosis before surgery. (UMIN000028505).

The ability of positron emission tomography/computed tomography to detect synchronous colonic cancers in patients with obstructive colorectal cancer

Positron emission tomography/computed tomography (PET/CT) is frequently used to detect colorectal cancer. The present retrospective study assessed the ability of PET/CT to identify synchronous colonic lesions in 72 patients with obstructive colorectal cancer. All patients had undergone surgical resection without undergoing preoperative total colonoscopy (TCS) at the Digestive Disease Center (April 2007 to September 2016), and subsequently underwent TCS of the proximal colon within 2 years post-surgery. A total of 11 patients exhibited 18F-fluorodeoxyglucose uptake during PET/CT of the proximal colon (4 invasive cancers, 3 advanced adenomas and 4 false-positive results), and 61 patients had no uptake in the proximal colon. Among these 61 patients, postoperative TCS revealed 2 invasive cancers and 4 advanced adenomas. The sensitivity of PET/CT for detecting synchronous invasive cancers was 66.6% (4/6), with a specificity of 89.4% (59/66), a positive predictive value of 36.4% (4/11), a negative predictive value of 96.7% (59/61), and an accuracy of 87.5% (63/72). Negative PET/CT results indicated a low probability of synchronous lesions in the proximal colon. Thus, PET/CT may be a useful tool for detecting synchronous colonic cancers in patients with obstructive colon cancer.

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.

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.

Clinical Value of CT Colonography Versus Preoperative Colonoscopy in the Surgical Management of Occlusive Colorectal Cancer

OBJECTIVE

CT colonography (CTC) has been recognized as a complementary approach to evaluating the entire colon after incomplete colonoscopy (IC) in patients with occlusive colorectal cancer (CRC). The objective of this study is to evaluate changes in preoperative surgical planning after CTC is performed for patients with occlusive CRC and IC in an oncologic hospital.

MATERIALS AND METHODS

This retrospective study included 65 consecutive patients with occlusive CRC who underwent CTC after IC at our institution from February 2000 to April 2016. CTC examinations and radiology reports were reviewed by an abdominal radiologist. Clinical information was obtained from a review of the electronic medical record.

RESULTS

CTC contributed to a change in the initial surgical plan of the surgeon for 14 of 65 patients (21.5%). In these 14 patients, CTC detected five synchronous proximal colon polyps (35.7%), five synchronous proximal cancers (35.7%), two imprecise CRC locations (14.3%), one case of proximal colon ischemia (7.1%), and one instance of tumor infiltration of the urinary bladder (7.1%). All CTC findings were confirmed at surgery, and all proximal colon polyps were subsequently confirmed to be advanced adenomas.

CONCLUSION

The preoperative CTC findings optimized the surgical management plan for 21.5% of patients with occlusive CRC and IC.

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.

Comparison of 64-Detector CT Colonography and Conventional Colonoscopy in the Detection of Colorectal Lesions

Background:

Colon cancer is a leading cause of morbidity and mortality in developed countries. The early detection of colorectal cancer using screening programs is important for managing early-stage colorectal cancers and polyps. Modalities that allow examination of the entire colon are conventional colonoscopy, double contrast barium enema examination and multi-detector computed tomography (MDCT) colonography.

Objectives:

To compare CT colonography and conventional colonoscopy results and to evaluate the accuracy of CT colonography for detecting colorectal lesions.

Patients and Methods:

In a prospective study performed at Gastroenterology and Radiology Departments of Medical Faculty of Eskisehir Osmangazi University, CT colonography and colonoscopy results of 31 patients with family history of colorectal carcinoma, personal or family history of colorectal polyps, lower gastrointestinal tract bleeding, change in bowel habits, iron deficiency anemia and abdominal pain were compared. Regardless of the size, CT colonography and conventional colonoscopy findings for all the lesions were cross - tabulated and the sensitivity, specificity, and positive and negative predictive values were calculated. To assess the agreement between CT colonography and conventional colonoscopy examinations, the Kappa coefficient of agreementt was used. Statistical analysis was performed by SPSS ver 15.0.

Results:

Regardless of the size, MDCT colonography showed 83% sensitivity and 95% specificity, with a positive predictive value of 95% and a negative predictive value of 83% for the detection of colorectal polyps and masses. MDCT colonography displayed 92% sensitivity and 95% specificity, with a positive predictive value of 92% and a negative predictive value of 95% for polyps ≥ 10 mm. For polyps between 6mm and 9 mm, MDCT colonography displayed 75% sensitivity and 100% specificity, with a positive predictive value of 100% and a negative predictive value of 90%. For polyps ≤ 5 mm MDCT colonography displayed 88% sensitivity and 100% specificity with a positive predictive value of 100% and a negative predictive value of 95%.

Conclusions:

CT colonography is a safe and minimally invasive technique, a valuable diagnostic tool for examining the entire colon and a good alternative compared to other colorectal cancer screening tests because of its high sensitivity values in colorectal lesions over 1 cm.

Perioperative Colonic Evaluation in Patients with Rectal Cancer; MR Colonography Versus Standard Care

RATIONALE AND OBJECTIVES

Preoperative colonic evaluation is often inadequate because of cancer stenosis making a full conventional colonoscopy (CC) impossible. In several studies, cancer stenosis has been shown in up to 16%-34% of patients with colorectal cancer. The purpose of this study was to prospectively evaluate the completion rate of preoperative colonic evaluation and the quality of perioperative colonic evaluation using magnetic resonance colonography (MRC) in patients with rectal cancer.

MATERIALS AND METHODS

Patients diagnosed with rectal cancer were randomized to either group A: standard preoperative diagnostic work-up or group B: preoperative MR diagnostic work-up (standard preoperative diagnostic work-up + MRC). A complete and adequate perioperative clean-colon evaluation (PCE) was defined as either a complete preoperative colonic evaluation or a complete colonic evaluation within 3 months postoperatively.

RESULTS

Twenty-eight patients were randomized to group A and 28 to group B. Complete preoperative colonic evaluation with CC was achieved in 39% patients in group A and 93% for group B (Fisher's exact test, P < .001). PCE with CC was achieved in 64% and 93% in groups A and B, respectively (Fisher's exact test, P = .02). In group A, one synchronous cancer was found by CC. However, the location was misjudged as a sigmoid cancer. In group B, two synchronous cancers were found in the same patient who had an insufficient preoperative CC due to an obstructing rectal cancer.

CONCLUSIONS

MRC is a valuable tool and is recommended as part of the standard preoperative evaluation for patients with rectal cancer.

Staging of colorectal cancer using contrast-enhanced multidetector computed tomographic colonography

INTRODUCTION

Preoperative staging is essential for the optimal treatment and surgical planning of colorectal cancers. This study was aimed to evaluate the accuracy of colorectal cancer staging done using contrast-enhanced multidetector computed tomographic colonography (CEMDCTC).

METHODS

We recruited 25 patients with 28 proven colorectal cancers. A 16-slice multidetector computed tomography scanner was used to generate two-dimensional multiplanar reformatted sagittal, coronal and oblique coronal images, and three-dimensional virtual colonography (endoluminal) images. Axial and reformatted views were analysed, and TNM staging was done. Patients underwent surgery and conventional colonoscopy, and surgical histopathological correlation was obtained.

RESULTS

The diagnostic accuracies for TNM colorectal cancer staging were 92.3% for T staging, 42.3% for N staging and 96.1% for M staging using CEMDCTC. There was excellent positive correlation for T staging between CEMDCTC and both surgery (κ-value = 0.686) and histopathology (κ-value = 0.838) (p < 0.0001), and moderate positive correlation for N staging between CEMDCTC and surgery (κ-value = 0.424; p < 0.0001). The correlation between CEMDCTC and histopathology for N staging was poor (κ-value = 0.186; p < 0.05); the negative predictive value was 100% for lymph node detection. Moderate positive correlation was seen for M staging between CEMDCTC and both surgery (κ-value = 0.462) and histopathology (κ-value = 0.649). No false negatives were identified in any of the M0 cases.

CONCLUSION

CEMDCTC correlated well with pathologic T and M stages, but poorly with pathologic N stage. It is an extremely accurate tool for T staging, but cannot reliably distinguish between malignant lymph nodes and enlarged reactive lymph nodes.

Value of Virtual Colonoscopy with 64 Row CT in Evaluation of Colorectal Cancer

Background

Virtual colonoscopy (VC) enables three-dimensional view of walls and internal lumen of the colon as a result of reconstruction of multislice CT images. The role of VC in diagnosis of the colon abnormalities systematically increases, and in many medical centers all over the world is carried out as a screening test of patients with high risk of colorectal cancer.

Material/Methods

We analyzed results of virtual colonoscopy of 360 patients with clinical suspicion of colorectal cancer. Sensitivity and specificity of CT colonoscopy for detection of colon cancers and polyps were assessed.

Results

Results of our research have shown high diagnostic efficiency of CT colonoscopy in detection of focal lesions in large intestine of 10 mm or more diameter. Sensitivity was 85.7%, specificity 89.2%.

Conclusions

Virtual colonoscopy is noninvasive and well tolerated by patients imaging method, which permits for early detection of the large intestine lesions with specificity and sensitivity similar to classical colonoscopy in screening exams in patients suspected for colorectal cancer. Good preparation of the patients for the examination is very important for proper diagnosis and interpretation of this imaginge procedure.

Adenomatous neoplasia: postsurgical incidence after normal preoperative CT colonography findings in the colon proximal to an occlusive cancer

PURPOSE

To determine the postoperative incidence of adenomatous neoplasia in the colon proximal to an occlusive colorectal cancer where preoperative computed tomographic (CT) colonography findings were normal.

MATERIALS AND METHODS

Institutional review board approval, with a waiver of informed consent, was obtained. This observational study included patients with occlusive colorectal cancer who underwent preoperative CT colonography between April 2007 and March 2010 that revealed normal findings (ie, no lesions ≥ 6 mm) in the proximal colon and who underwent postoperative colonoscopy. The primary outcome was postoperative colonoscopic discovery of clinically relevant lesions (ie, nondiminutive [≥ 6 mm] adenomas, advanced adenomas, or cancers) in the proximal colon. The cumulative incidence of clinically relevant lesions in preoperatively normal proximal colon over the postsurgical follow-up time was analyzed by using the Kaplan-Meier method.

RESULTS

The final cohort included 204 patients (102 men and 102 women; mean age, 57.3 years ± 11.3 [standard deviation]). At a total of 435 postoperative colonoscopies performed over a median follow-up of 29 months (range, 1-74 months), clinically relevant lesions were detected in the proximal colon in 30 patients: Nonadvanced adenomas were detected in 23 patients, and advanced adenomas were detected in seven patients. The cumulative incidence of clinically relevant adenomatous lesions in the preoperatively normal proximal colon 12 and 18 months after preoperative CT colonography was 8.1% (95% confidence interval [CI]: 3.9%, 12.2%) and 9.6% (95% CI: 5%, 14%), respectively. Clinically relevant adenomatous lesions found in the proximal colon within 18 months of preoperative CT colonography were nonadvanced adenomas in 10 of 15 patients.

CONCLUSION

When the portion of the colon proximal to an occlusive cancer is devoid of nondiminutive lesions at preoperative CT colonography, colonoscopy of the proximal colon following cancer resection rarely finds clinically relevant lesions and is unlikely to reveal any lesions requiring immediate removal until routine 1-year postsurgical follow-up. Online supplemental material is available for this article .

Impact of contrast-enhanced computed tomography colonography on laparoscopic surgical planning of colorectal cancer

AIM

To evaluate the impact of contrast-enhanced computed tomography colonography (CE-CTC) on laparoscopic surgery planning in patient with stenosing colorectal cancer.

MATERIALS AND METHODS

Sixty-nine patients with endoscopically proven colorectal cancer underwent CE-CTC, after incomplete conventional colonoscopy. Two experienced radiologists evaluated site, length, and TNM staging of colorectal cancers on three-dimensional double contrast enema-like views, 2D axial and multiplanar reconstructions. All the patients underwent colorectal resection and surgery bulletin, pathology of surgical specimens, and radiological follow-up at about 8 months were used as reference standard.

RESULTS

The detection rate of colorectal cancer was 100 % (75/75); CE-CTC allowed for a diagnosis of a synchronous colorectal cancer in five patients (7 %). CE-CTC correctly judged the site of the lesions in all the cases; clinically significant localization errors at conventional colonoscopy were noted in 3 out of 69 patients (4 %). Additional colonic polyps greater than 6 mm in diameter were found in 21 out of 69 patients (30 %); in two patients (3 %) the surgeon performed an enlarged colectomy to include synchronous polyps proximal to colorectal cancer. Sensitivity, specificity, PPV, NPV, and accuracy were for T1-T2 vs. T3-T4: 96 %, 71 %, 92 %, 87 %, and 91 %, respectively; for N: 94 %, 42 %, 64 %, 86 %, and 70 %; for M: 100 %, 100 %, 83 %, 100 %, and 97 %. There were no complications associated with CE-CTC.

CONCLUSION

Information given by CE-CTC concerning colorectal cancer location and synchronous colonic cancers and polyps changed the laparoscopic surgical strategy in almost 14 % of patients.

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.

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.

Synchronous colorectal neoplasias: our experience about laparoscopic-TEM combined treatment

Synchronous colorectal neoplasias are defined as 2 or more primary tumors identified in the same patient and at the same time. The most voluminous synchronous cancer is called "first primitive" or "index" cancer. The aim of this work is to describe our experience of minimally invasive approach in patients with synchronous colorectal neoplasias.Since January 2001 till December 2009, 557 patients underwent colectomy for colorectal cancer at the Department of General and Emergency Surgery of the University of Perugia; 128 were right colon cancers, 195 were left colon cancers while 234 patients were affected by rectal cancers. We performed 224 laparoscopic colectomies (112 right, 67 left colectomies and 45 anterior resections of rectum), 91 Transanal Endoscopic Microsurgical Excisions (TEM) and 53 Trans Anal Excisions (TAE). In the same observation period 6 patients, 4 males and 2 females, were diagnosed with synchronous colorectal neoplasias. Minimal invasive treatment of colorectal cancer offers the opportunity to treat two different neoplastic lesions at the same time, with a shorter post-operative hospitalization and minor complications. According to our experience, laparoscopy and TEM may ease the treatment of synchronous diseases with a lower morbidity rate.

Risk factors for colonic perforation after screening computed tomographic colonography: a multicentre analysis and review of the literature

BACKGROUND

Computed tomographic (CT) colonography (or 'virtual' colonoscopy) has become an increasingly popular tool for colorectal cancer screening. Colonic perforation, an uncommon complication, is a risk that has not been widely reported.

METHODS

A systematic review of the literature was undertaken to identify all reported risk factors for colonic perforation following CT colonography. In addition, a retrospective multicentre study was undertaken, evaluating all CT colonographies in 10 major metropolitan tertiary referral centres. All colonic perforations were assessed for risk factors.

RESULTS

A range of 'patient'-related and 'procedure'-related risk factors were identified in the literature. Among 3458 CT colonographies, there were two cases of colonic perforation contributing to an incidence of perforation of 0.06%. There was no statistical correlation between the incidence of perforation and institutional experience (P = 0.66). Risk factors common to both cases and the literature included age, recent colonoscopy and manual colonic insufflation. Diverticular disease and recent colonic biopsy were also notable factors.

CONCLUSION

There is a small but real risk of perforation following CT colonography. Patient selection and preventative procedural measures may reduce this risk. The importance of the consent process is emphasized.

CT colonography after metallic stent placement for acute malignant colonic obstruction

PURPOSE

To evaluate the feasibility of using computed tomographic (CT) colonography for preoperative examination of the proximal colon after metallic stent placement in patients with acute colon obstruction caused by colorectal cancer.

MATERIALS AND METHODS

Institutional review board approval was obtained, and patient informed consent was waived. Fifty patients (mean age +/- standard deviation, 58.5 years +/- 11.7), who demonstrated no postprocedural complication after successful placement of self-expandable metallic stents to treat acute colon obstruction caused by cancer, underwent CT colonography 1-43 days (median, 5 days) after stent placement. CT colonography was performed after cathartic preparation by using magnesium citrate (n = 20) or sodium phosphate (n = 3), combined with oral bisacodyl, or by using polyethylene glycol (n = 27). Fecal/fluid tagging was achieved by using 100 mL of meglumine diatrizoate. The colon was distended by means of pressure-monitored CO(2) insufflation. The sensitivity and specificity of CT colonography in evaluating the colon proximal to the stent and CT colonography-related complications were assessed. The 95% confidence intervals (CIs) were calculated for proportional data.

RESULTS

Per-lesion and per-patient sensitivities of CT colonography for lesions 6 mm or larger in diameter in the colon proximal to the stent were 85.7% (12 of 14 lesions; 95% CI: 58.8%, 97.2%) and 90% (nine of 10 patients; 95% CI: 57.4%, 99.9%), respectively. CT colonography depicted all synchronous cancers (two lesions) and advanced adenomas (five lesions). Per-patient specificity for lesions 6 mm and larger in the proximal colon was 85.7% (18 of 21 patients; 95% CI: 64.5%, 95.9%). CT colonography did not generate any false diagnosis of synchronous cancer. False-positive findings at CT colonography did not result in a change in surgical plan for any patients. No CT colonography-associated stent dislodgment/migration or colonic perforation occurred in any patient (95% CI: 0%, 6.2%).

CONCLUSION

CT colonography is a safe and useful method for preoperative examination of the proximal colon after metallic stent placement in patients with acute colon obstruction caused by cancer. (c) RSNA, 2010.

Computed tomographic colonography: Hope or hype?

Computed tomographic colonography (CTC) is a promising emerging technology for imaging of the colon. This concise review discusses the currently available data on CTC technique, test characteristics, acceptance, safety, cost-effectiveness, follow-up strategy, and extracolonic findings. In summary, CTC technique is still evolving, and further research is needed to clarify the role of automated colonic insufflation, smooth-muscle relaxants, intravenous and oral contrast, software rendering, and patient positioning. Currently, full bowel preparation is still required to achieve optimal results. The sensitivity for detecting large polyps (> 1 cm) can be as high as 85%, with specificity of up to 97%. These test characteristics are almost comparable to those of conventional colonoscopy. Patient acceptance of CTC is generally higher than that for colonoscopy, especially in patients who have never undergone either procedure. CTC is generally safe, although uncommon instances of colonic perforation have been documented. In terms of cost-effectiveness, most decision analyses have concluded that CTC would only be cost-effective if it were considerably cheaper than conventional colonoscopy. The proper follow-up strategy for small polyps or incidental extracolonic findings discovered during CTC is still under debate. At present, the exact clinical role of virtual colonoscopy still awaits determination. Even though widespread CTC screening is not available today, in the future there may eventually be a role for this technology. Technological advances in this area will undoubtedly continue, with multi-detector row CT scanners allowing thinner collimation and higher resolution images. Stool-tagging techniques are likely to evolve and may eventually allow for low-preparation CTC. Perceptual and fatigue-related reading errors can potentially be minimized with the help of computer-aided detection software. Further research will define the exact role of this promising technology in our diagnostic armamentarium.

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.

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.

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.

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.

Preoperative evaluation of synchronous colorectal cancer using MR colonography

RATIONALE AND OBJECTIVES

It is well known that synchronous cancers (incidence, 2%-11%) and polyps (incidence, 12%-58%) occur in patients with colorectal cancer. Magnetic resonance colonography (MRC) seems like the obvious choice as a diagnostic tool in preoperative evaluation, because it is noninvasive, and most of the colon can be evaluated. Furthermore, it has higher patient acceptance, and no sedation or radiation is used. The purpose of this study was to determine the feasibility of performing MRC preoperatively in an everyday clinical situation in a group of patients who were not offered a full conventional colonoscopy or in whom full conventional colonoscopy was not possible.

MATERIALS AND METHODS

In a 13-month period, 47 patients diagnosed with rectal or sigmoid colon cancer scheduled for operation were included in the study. MRC was performed with bowel purgation either the night before surgery or as ambulatory MRC the week before surgery.

RESULTS

Full MRC was performed in 98% of the patients. In four patients, 12 synchronous lesions (one cancer, two plaques of carcinosis, and nine adenomas) were found. One flat adenoma and five small polyps were missed by MRC and perioperative palpation but found on postoperative colonoscopy. The findings resulted in altered operative strategies in three patients.

CONCLUSION

This study shows the feasibility and potential gain of preoperative MRC in patients with sigmoid colon cancer or rectal cancer.

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.

Virtual colonoscopy vs conventional colonoscopy in patients at high risk of colorectal cancer--a prospective trial of 150 patients

OBJECTIVE

Virtual colonoscopy (VC)/CT colonography has advantages over the well-documented limitations of colonoscopy/barium enema. This prospective blinded investigative comparison trial aimed to evaluate the ability of VC to assess the large bowel, compared to conventional colonoscopy (CC), in patients at high risk of colorectal cancer (CRC).

METHOD

We studied 150 patients (73 males, mean age 60.9 years) at high risk of CRC. Following bowel preparation, VC was undertaken using colonic insufflation and 2D-spiral CT acquisition. Two radiologists reported the images and a consensual agreement reached. Direct comparison was made with CC (performed later the same day). Interobserver agreement was calculated using the Kappa method. Postal questionnaires sought patient preference.

RESULTS

Virtual colonoscopy visualized the caecum in all cases. Five (3.33%) VCs were classified as inadequate owing to poor distension/faecal residue. CC completion rate was 86%. Ultimately, 44 patients had normal findings, 44 had diverticular disease, 11 had inflammatory bowel disease, 18 had cancers, and 33 patients had 42 polyps. VC identified 19 cancers--a sensitivity and specificity of 100% and 99.2% respectively. For detecting polyps > 10 mm, VC had a sensitivity and specificity (per patient) of 91% and 99.2% respectively. VC identified four polyps proximal to stenosing carcinomas and extracolonic malignancies in nine patients (6%). No procedural complications occurred with either investigation. A Kappa score achieved for interobserver agreement was 0.777.

CONCLUSION

Virtual colonoscopy is an effective and safe method for evaluating the bowel and was the investigation of choice amongst patients surveyed. VC provided information additional to CC on both proximal and extracolonic pathology. VC may become the diagnostic procedure of choice for symptomatic patients at high risk of CRC, with CC being reserved for therapeutic intervention, or where a tissue diagnosis is required.

The association of anisakiasis in the ascending colon with sigmoid colon cancer: CT colonography findings

The association of anisakiasis of the colon with colon cancer is rare and difficult to diagnose. Only one case of this type has been reported to date. In this study, we report a case of synchronous colon cancer and colonic anisakiasis. A 50-year-old woman was admitted for abdominal pain, and a volume-rendered surface-shaded image of CT colonography (CTC) revealed a concentric narrowing in the sigmoid colon and a segmental fold thickening in the ascending colon. A total colectomy was performed and the diagnosis of synchronous sigmoid colon cancer and anisakiasis of the ascending colon was confirmed. This case is the first reported visualization of synchronous colon cancer and colonic anisakiasis on a CTC.

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.

PET/CT colonography for the preoperative evaluation of the colon proximal to the obstructive colorectal cancer

PURPOSE

This study was designed to evaluate the usefulness of 18-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) colonography in preoperative diagnosis of the tumors proximal to obstructive colorectal cancers, which were defined as cancers that cannot be traversed colonoscopically.

METHODS

A whole-body PET/CT protocol for tumor staging and a protocol for CT colonography were integrated into one examination. No cathartic bowel preparation was used before this examination. Thirteen prospective patients with obstructive cancer were examined. We compared the detection rates for obstructive colorectal cancers and tumors proximal to the obstruction using air-inflated PET/CT colonography to intraoperative examinations, histopathologic outcome, and follow-up colonoscopy.

RESULTS

PET/CT colonography correctly identified all 13 primary obstructive colorectal cancers and all 2 synchronous colon cancers proximal to the obstruction. The two synchronous colon cancers detected at PET/CT colonography were confirmed and removed at single-stage surgical procedures. PET/CT colonography was able to localize all colorectal cancers precisely. There were no false-negative or false-positive proximal colorectal cancers by PET/CT colonography. Other preoperative examinations missed the synchronous colon cancers.

CONCLUSIONS

In patients with obstructive colorectal cancers, preoperative PET/CT colonography provided valuable anatomic and functional information of the entire colon to properly address surgery of colorectal cancer.

Automated carbon dioxide insufflation for CT colonography: effectiveness of colonic distention in cancer patients with severe luminal narrowing

OBJECTIVE

The objective of our study was to determine the effectiveness of automated CO2 insufflation in colonic distention for CT colonography (CTC) in patients with severe luminal narrowing by colorectal cancer and preliminarily evaluate its safety performed shortly after colonoscopic polypectomy or biopsy.

MATERIALS AND METHODS

Seventy-four patients were examined with colonoscopy and subsequent CTC (time interval, 0-8 days) using automated CO2 insufflation. Thirty-six patients whose colonoscopy was incomplete due to severe luminal narrowing by cancer that prevented colonoscope passage constituted the stenotic group. The remaining 38 patients constituted the nonstenotic group. Colonic distention was graded by two experienced readers from 1 (worst) to 4 (best) and compared between the two groups. Clinical data and CT images were analyzed for the occurrence of colonic perforation.

RESULTS

Distention was not significantly different between the stenotic and nonstenotic groups in any colonic segments in both supine and prone positions. The mean distention grade +/- SD of the colonic segments proximal to the luminal narrowing in the stenotic group (n = 143 segments) was 3.7 +/- 0.7 and 3.8 +/- 0.7 for the supine and prone positions, respectively. Colonic perforation was not noted in any of the 74 patients, including 65 patients who underwent CTC within 24 hours after colonoscopy (62 snare polypectomies, two polypectomies using biopsy forceps, 63 routine mucosal biopsies).

CONCLUSION

Automated pressure-controlled CO2 insufflation is as efficient in colonic distention for CTC in colorectal cancer patients with severe luminal narrowing as it is in patients without severe luminal narrowing.

Is there still a role for double-contrast barium enema examination?

The role of double-contrast barium enema examination (DCBE) in screening for colorectal carcinoma has evolved considerably in recent years. This review will discuss the current indications for DCBE and contrast fluoroscopy of the colon and the anticipated future role of these studies.

CT colonography: current status and future promise

CT colonography (CTC) is an innovative technology that entails CT examination of the entire colon and computerized processing of the raw data after colon cleansing and colonic distention. CTC could potentially increase the screening rate for colon cancer because of its relative safety, relatively low expense, and greater patient acceptance, but its role in mass colon cancer screening is controversial because of its highly variable sensitivity, the inability to sample polyps for histologic analysis, and lack of therapeutic capabilities. This article reviews the CTC literature, including imaging and adjunctive techniques, radiologic interpretation, procedure indications, contraindications, risks, sensitivity, interpretation pitfalls, and controversies.

Computed tomography colonography compared with conventional colonoscopy for the detection of colorectal polyps

OBJECTIVE

To determine the diagnostic accuracy of computed tomography colonography (CTC) compared with conventional colonoscopy (CC).

METHODS

Patients with an indication of CC were included. Fifty patients underwent CTC using multidetector CT before diagnostic colonoscopy was performed by an expert colonoscopist. Diagnostic accuracy was assessed individually both for each polyp and for each patient.

RESULTS

Fifty patients were included and 40 polyps were analyzed. The by-polyp sensitivity of CTC was 15% for polyps 5 mm or less, 75% for polyps 5- 10 mm and 75% for polyps 10 mm or larger. By-patient specificity was 6% for polyps 5 mm or less, 75% for polyps 5-10 mm and 80% for polyps 10 mm or larger. The specificity of CTC was 94%. CTC was preferred over CC by 90% of the patients. The mean colonoscopy examination time was 30 minutes for CC and 35 minutes for CTC (p < 0.05).

CONCLUSIONS

The sensitivity of CTC is moderate in detecting polyps larger than 10 mm, low in detecting 5-10 mm polyps and very low in detecting those less than 5 mm. The overall specificity of the procedure was 94%. Procedure time was lower with CC than with CTC but the latter was better tolerated by most patients.

Incomplete colonoscopy in patients with occlusive colorectal cancer: usefulness of CT colonography according to tumor location

PURPOSE

We sought to evaluate the clinical usefulness of CT colonography (CTC) after incomplete conventional colonoscopy (CC) for occlusive colorectal cancer (CRC) according to the tumor location.

MATERIALS AND METHODS

Seventy-five patients with occlusive CRC underwent subsequent CTC immediately after incomplete CC. Fifty-nine patients had distal CRC and 16 had proximal colon cancer. Experienced radiologists prospectively analyzed the location, length, and TNM staging of the main tumor. The colorectal polyps in the remaining colorectum and additional extraluminal findings were also recorded. Sixty-seven patients underwent colorectal resection. We retrospectively analyzed the surgical outcome and correlated CTC and CC findings.

RESULTS

The overall accuracies of tumor staging were: T staging, 86%; N staging (nodal positivity), 70% (80%); and intra-abdominal M staging, 94%. Additional colonic polyps were found in 23 patients. Six synchronous carcinomas were detected (9%); three in the proximal colon and three in the distal colon of occlusion. Clinically significant localization errors at CC were noted in 8 patients (12%, 5 proximal colon cancers and 3 distal CRCs) and were corrected by CTC. After CTC, the surgeons modified the initial surgical plan in 11 cases (16%).

CONCLUSION

In occlusive CRC, CTC is not only useful in the evaluation of the proximal bowel, but can also provide surgeons with accurate information about staging and tumor localization. CTC is recommended when endoscopists encounter occlusive CRC, regardless of tumor location.