Computed Tomography Colonography Versus Standard Optical Colonoscopy for the Detection of Colorectal Polyp in Patients Who Faced Curative Surgery for Colorectal Cancer: A Diagnostic Performance Study.

Data regarding computed tomography colonography, standard optical colonoscopy, and enhanced colonoscopy/histopathology at 1-year after surgery and at 6-month intervals for the next 2 years of 345 patients who faced curative surgery for colorectal cancer were included in this analysis. Computed tomography colonography and standard optical colonoscopy both detected 298 polyps as suspicious. With reference to enhanced colonoscopy/histopathology, sensitivities for the detection of any polyps for computed tomography colonography and standard optical colonoscopy were 0.952 and 0.906, while, accuracies were 0.783 and 0.641, respectively. Computed tomography colonography may be a sensitive and accurate surveillance tool for colorectal cancer patients.

Capsule endoscopy vs. colonoscopy vs. histopathology in colorectal cancer screening: matched analyses of polyp size, morphology, and location estimates.

PURPOSE: Colon capsule endoscopy (CCE) is considered a potential alternative to optical colonoscopy (OC) for colorectal cancer screening. However, the accuracy of CCE in polyp size and morphology estimation is unknown. METHODS: A fully paired study was performed (2015-2016), where 255 participants from the Danish national screening program had CCE, OC, and histopathology (HP) of all detected polyps. We developed a new algorithm to match CCE and OC polyps, based on objective measures of similarity between polyps. We performed paired comparisons of size, morphology and location of CCE, and OC- and HP-matched polyps. We used cross-validation to develop a model able to predict HP polyp size, based on CCE. RESULTS: CCE overestimated size assessed by HP (by 4.3 mm; 95%CI 3.3-5.2 mm) and OC (by 2.7 mm; 95%CI 1.4-3.9 mm). Polyps were more likely to being assessed as "pedunculated" and less likely to being assessed as "flat" in CCE, compared to OC (p < 0.0001). Our model could predict HP polyp size ≥ 6 mm, solely using CCE-assessed size, location, and morphology as model inputs, with a sensitivity = 0.93 (95%CI 0.66-1.00) and specificity = 0.50 (95%CI 0.32-0.68). CONCLUSIONS: If CCE is to be used as a screening test, it is essential: (1) to translate CCE polyp estimations into histopathologic polyp sizes and (2) to consider that, compared to OC, CCE has a higher tendency to assess polyps as pedunculated and a lower tendency to assess them as flat. TRIAL REGISTRATION: Clinicaltrials.gov No. NCT02303756.

Acute Abdominal Pain Following Optical Colonoscopy: CT Findings and Clinical Considerations.

OBJECTIVE: Optical colonoscopy is a common procedure; more than 14 million are performed annually in the United States. Serious colonoscopy complications are uncommon, but they can be life-threatening if not quickly recognized. CONCLUSION: Optical colonoscopy complications that can be detected at CT include bowel perforation, postprocedural hemorrhage, postpolypectomy syndrome, splenic injury, appendicitis, and diverticulitis. Radiologist awareness of optical colonoscopy complications seen at CT is imperative for appropriate diagnosis and prompt patient management.

Medicare cost of colorectal cancer screening: CT colonography vs. optical colonoscopy.

PURPOSE: To compare the Medicare population cost of colorectal cancer (CRC) screening of average risk individuals by CT colonography (CTC) vs. optical colonoscopy (OC). METHODS: The authors used Medicare claims data, fee schedules, established protocols, and other sources to estimate CTC and OC per-screen costs, including the costs of OC referrals for a subset of CTC patients. They then modeled and compared the Medicare costs of patients who complied with CTC and OC screening recommendations and tested alternative scenarios. RESULTS: CTC is 29% less expensive than OC for the Medicare population in the base scenario. Although the CTC cost advantage is increased or reduced under alternative scenarios, it is always positive. CONCLUSION: CTC is a cost-effective CRC screening option for the Medicare population and will likely reduce Medicare expenditures for CRC screening.

Accuracy of capsule colonoscopy and computed tomographic colonography in individuals with positive results from the fecal occult blood test.

BACKGROUND & AIMS: Computed tomographic colonography (CTC) is a reliable option for screening subjects who are unable or unwilling to undergo optical colonoscopy (OC). A colon capsule (PillCam Colon2 [CC2]; GivenImaging Ltd., Yokneam, Israel) has shown promising results in detecting polyps larger than 6 mm. We compared the accuracy of CC2 and CTC in identifying individuals with at least 1 polyp greater than 6 mm and subjects' attitude toward the procedures. METHODS: Fifty individuals (mean age, 59.2 ± 5.8 y; 58% male) with positive results from the immunochemical fecal occult blood test (iFOBT-positive) underwent CC2, CTC, and OC. The unblinded colonoscopy, integrating OC, CTC, and CC2 results, was used as the reference standard. In a per-patient analysis, the accuracy of CC2 and CTC were assessed for individuals with at least 1 polyp 6 mm or larger. Individuals were asked to choose which procedure they would be willing to repeat between CTC and CC2. RESULTS: The combination of OC, CTC, and CC2 identified 16 cases with at least 1 polyp 6 mm or larger (reference standard). CTC identified the polyps with 88.2% sensitivity, 84.8% specificity, a 3.0 positive likelihood ratio, and a 0.07 negative likelihood ratio. CC2 identified the polyps with 88.2% sensitivity, 87.8% specificity, a 3.75 positive likelihood ratio, and a 0.06 negative likelihood ratio. Thirty-nine subjects (78%) said they preferred CC2 to CTC. CONCLUSIONS: CC2 and CTC detect polyps 6 mm and larger with high levels of accuracy; these techniques are effective in selecting iFOBT-positive individuals who do not need to be referred for colonoscopy. CC2 seems to be better tolerated than CTC, and could be a reliable alternative to CTC for iFOBT-positive individuals who are unable or unwilling to undergo OC. ClinicalTrials.gov number: NCT01744509.

A non-aligned translation with a neoplastic classifier regularization to include vascular NBI patterns in standard colonoscopies.

Polyp vascular patterns are key to categorizing colorectal cancer malignancy. These patterns are typically observed in situ from specialized narrow-band images (NBI). Nonetheless, such vascular characterization is lost from standard colonoscopies (the primary attention mechanism). Besides, even for NBI observations, the categorization remains biased for expert observations, reporting errors in classification from 59.5% to 84.2%. This work introduces an end-to-end computational strategy to enhance in situ standard colonoscopy observations, including vascular patterns typically observed from NBI mechanisms. These retrieved synthetic images are achieved by adjusting a deep representation under a non-aligned translation task from optical colonoscopy (OC) to NBI. The introduced scheme includes an architecture to discriminate enhanced neoplastic patterns achieving a remarkable separation into the embedding representation. The proposed approach was validated in a public dataset with a total of 76 sequences, including standard optical sequences and the respective NBI observations. The enhanced optical sequences were automatically classified among adenomas and hyperplastic samples achieving an F1-score of 0.86%. To measure the sensibility capability of the proposed approach, serrated samples were projected to the trained architecture. In this experiment, statistical differences from three classes with a ρ-value <0.05 were reported, following a Mann-Whitney U test. This work showed remarkable polyp discrimination results in enhancing OC sequences regarding typical NBI patterns. This method also learns polyp class distributions under the unpaired criteria (close to real practice), with the capability to separate serrated samples from adenomas and hyperplastic ones.

Incidence of clinically significant perforation at low dose non-contrast CT and its value prior to same day CT colonography following incomplete colonoscopy.

PURPOSE: Routine low dose non-contrast CT of the abdomen and pelvis has been suggested prior to same day completion CT colonography (CTC) to assess for occult perforation at preceding incomplete colonoscopy, before further gaseous insufflation at CTC. The aim of our study is to examine the incidence of clinically significant perforation at low dose CT. We also examine the benefits of low dose pre-scan in assessing adequacy of bowel preparation and identifying any other relevant contraindications to CT colonography. MATERIALS AND METHODS: We conducted a retrospective review of all low dose non-contrast CTs performed following failed colonoscopies over a 4-year period (n = 392). We also assessed the adequacy of bowel preparation on a scale of 1-5, in order of increasingly adequate preparation. Incidentally noted bowel pathology and contraindications to CT colonography were also recorded. RESULTS: No perforation was identified either prospectively or in the course of our retrospective review. However, 15 patients (3.8%) were found to have potential contraindications to CT colonography, including: acute diverticulitis, acute colitis, and poor bowel preparation. Overall, the bowel preparation was felt to be adequate (≥ 3) in 86% percent of patients. Two patients (0.5%) identified prospectively had their CT colonography postponed due to poor bowel preparation.

Colon capsule endoscopy versus CT colonography after incomplete colonoscopy. Application of artificial intelligence algorithms to identify complete colonic investigations.

BACKGROUND: Guidelines suggest computed tomography colonography (CTC) following incomplete optical colonoscopy (OC). Colon capsule endoscopies (CCE) have been suggested as an alternative, although completion rates have been unsatisfactory. Introduction of artificial intelligence (AI)-based localization algorithms of the camera capsules may enable identification of incomplete CCE investigations overlapping with incomplete OCs. OBJECTIVE: The study aims to investigate relative sensitivity of CCE compared with CTC following incomplete OC, investigate the completion rate when combining results from the incomplete OC and CCE, and develop a forward-tracking algorithm ensuring a safe completeness of combined investigations. METHODS: In this prospective paired study, patients with indication for CTC following incomplete OC were included for CCE and CTC. Location of CCE abortion and OC abortion were registered to identify complete combined investigations. AI-based algorithm for localization of capsules were developed reconstructing the passage of the colon. RESULTS: In 237 individuals with CTC indication; 105 were included, of which 97 underwent both a CCE and CTC. CCE was complete in 66 (68%). Including CCEs which reached most oral point of incomplete OC, 73 (75%) had complete colonic investigations; 78 (80%) had conclusive investigations. Relative sensitivity of CCE compared with CTC was 2.67 (95% confidence interval (CI) 1.76;4.04) for polyps >5 mm and 1.91 (95% CI 1.18;3.09) for polyps >9 mm. An AI-based algorithm was developed. CONCLUSION: Sensitivity of CCE following incomplete OC was superior to CTC. Introducing and improving algorithm-based localization of capsule abortion may increase identification of overall complete investigation rates following incomplete OC.ClinicalTrials.gov identifier: NCT02826993.

Learning colon centreline from optical colonoscopy, a new way to generate a map of the internal colon surface.

Optical colonoscopy is known as a gold standard screening method in detecting and removing cancerous polyps. During this procedure, some polyps may be undetected due to their positions, not being covered by the camera or missed by the surgeon. In this Letter, the authors introduce a novel convolutional neural network (ConvNet) algorithm to map the internal colon surface to a 2D map (visibility map), which can be used to increase the awareness of clinicians about areas they might miss. This was achieved by leveraging a colonoscopy simulator to generate a dataset consisting of colonoscopy video frames and their corresponding colon centreline (CCL) points in 3D camera coordinates. A pair of video frames were used as input to a ConvNet, whereas the output was a point on the CCL and its direction vector. By knowing CCL for each frame and roughly modelling the colon as a cylinder, frames could be unrolled to build a visibility map. They validated their results using both simulated and real colonoscopy frames. Their results showed that using consecutive simulated frames to learn the CCL can be generalised to real colonoscopy video frames to generate a visibility map.

The Natural History of Colorectal Polyps: Overview of Predictive Static and Dynamic Features.

For decades, colorectal screening strategies have been largely driven by static features, particularly polyp size. Although cross-sectional features of polyp size, morphology, and location are important determinants of clinical relevance before histology, they lack any dynamic information on polyp growth rates. Computed tomography colonography allows for in vivo surveillance of colorectal polyps, providing volumetric growth rates that are providing new insights into tumorigenesis. In this article, existing cross-sectional and longitudinal data on colorectal polyps are reviewed, with an emphasis on how these features may affect clinical relevance and patient management.

Same-day colon capsule endoscopy is a viable means to assess unexplored colonic segments after incomplete colonoscopy in selected patients.

BACKGROUND: Same-day colon capsule endoscopy (CCE) immediately following incomplete optical colonoscopy (OC) would have a number of advantages for patients, while also presenting unique procedural challenges including the effect of sedation on capsule propulsion and patient tolerance of protracted preparation and fasting. AIM: The aim of this article is to prospectively assess the efficacy of same-day CCE after incomplete OC in an unselected patient cohort. METHODS: This was an observational, prospective, single-centre study of CCE post-incomplete colonoscopies. Patients with an incomplete OC for any reason other than obstruction or inadequate bowel preparation were recruited. CCE was performed after a minimum of a one-hour fast. Once the patient was fully alert, intravenous metoclopramide was administered after capsule ingestion when possible, and a standard CCE booster protocol was then followed. Relevant clinical information was recorded. CCE completion rates, findings and their impact, and adverse events were noted. RESULTS: Fifty patients were recruited, mean age = 57 years and 66% (n = 32) were female. Seventy-six per cent (n = 38) of CCEs were complete; however, full colonic views were obtained in 84% (n = 42) of cases. Patients > 50 years of age were five times more likely to have an incomplete CCE and there was also a trend towards known comorbidities associated with hypomobility having reduced excretion rates. Overall diagnostic yield for CCE in the unexplored segments was 74% (n = 37), with 26% (n = 13) of patients requiring significant changes in management based on CCE findings. The overall incremental yield was 38%. CCE findings were normal 26% (n = 13), polyps 38% (n = 19), inflammation 22% (n = 11), diverticular disease 25 (n = 12), angiodysplasia 3% (n = 1) and cancer 3% (n = 1). Significant small bowel findings were found in three (6%) cases, including Crohn's disease and a neuroendocrine tumour. A major adverse event occurred in one patient (2%), related to capsule retention. CONCLUSION: Same-day CCE is a viable alternative means to assess unexplored segments of the colon after incomplete OC in selected patients.

The added clinical value of performing CT colonography in patients with obstructing colorectal carcinoma.

BACKGROUND: A small percentage of incomplete optical colonoscopies (OCs) are the result of an obstructing tumor. According to current guidelines, CT colonography (CTC) is performed to prevent missing a synchronous tumor. The aim of this study was to evaluate how frequently a synchronous tumor was found on CTC and how often this led to a change in the surgical plan. METHODS: In this retrospective study, a total of 267 patients underwent CTC after an incomplete OC as a result of an obstructing colorectal carcinoma (CRC). Among them, 210 patients undergoing surgery met the inclusion criteria and were included in the analysis. The OC report, CTC report and surgical report of these patients were retrospectively evaluated for the presence of synchronous tumors using surgery and post-operative colonoscopy as the gold standard. RESULTS: Six of the 210 patients (2.9%) showed signs of a synchronous CRC proximal to the obstructing tumor on CTC. In three of these patients, a synchronous CRC was confirmed during surgery. All these tumors caused a change in the surgical plan. Three out of the six tumors found on CTC were found to be large, non-malignant polyps. All these polyps were located in the same segment as the obstructing tumor and therefore did not alter the surgical plan. CONCLUSION: In patients with obstructing CRC, the frequency of synchronous CRCs proximal to this lesion is low. Performing a CTC leads to a change in surgical plan based on the presence of these synchronous tumors in 1.4% of the cases. CTC should be employed as a one-stop shop in patients with an obstructing CRC.

Computed Tomography Colonography Less Costly Than Colonoscopy for Colorectal Cancer Screening of Commercially Insured Patients.

BACKGROUND: Computed tomography (CT) colonography's effectiveness, its associated patient advantages, and its potential role to increase colorectal cancer (CRC) screening rates have been demonstrated in previous research, but whether CT colonography has a cost advantage relative to optical colonoscopy for the commercially insured US population has not been assessed. OBJECTIVE: To compare the costs of CRC screening using CT colonography or optical colonoscopy for commercially insured people in the United States. METHODS: Using retrospective commercial healthcare claims data and peer-reviewed studies, we performed a simulated multiyear, matched-case comparison of the costs of CT and optical colonoscopies for CRC screening. We estimated commercial optical colonoscopy costs per screening based on the 2016 Truven Health MarketScan Commercial Database and ancillary services, such as bowel preparation, anesthesia, pathology, and complication costs. We developed 4 scenarios for CT colonography cost per screening using the ratio of commercial to Medicare fees, and calculated ancillary service and follow-up costs from payers' costs for these services when associated with optical colonoscopies. For comparison, we converted the costs per screening to the costs per screening year per person using real-world screening intervals that were obtained from peer-reviewed studies. RESULTS: In 2016, the average optical colonoscopy screening cost for commercial payers was $2033 (N = 406,068), or $340 per screening year per person. With our highest-cost CT colonography scenario, CT colonography costs 22% less, or $265 per screening year, than optical colonoscopy, mostly because of the advantages for patients of no anesthesia and the greatly reduced use of pathology services. CONCLUSIONS: The use of CT colonography for CRC testing offers effective screening, patient-centered advantages, and lower costs compared with optical colonoscopy, and may be particularly appealing to the currently unscreened population with commercial health insurance. If the availability of CT colonography expands to meet the increased demand for it, CT colonography could cost up to 50% less than optical colonoscopy per screening year.

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.

Impact of hysterectomy on three-dimensional rectosigmoid morphology and endoscopy performance: a pilot study.

OBJECTIVES: Assess differences in three-dimensional colonic metrics on CTC in women with or without hysterectomy following incomplete endoscopy to determine if there is a correlation between colonic morphology and incomplete colonoscopy after hysterectomy. METHODS: Quantitative rectosigmoid metrics were derived from CTC datasets of 37 women with hysterectomy and 36 women without hysterectomy who underwent CTC for incomplete endoscopy. Evaluated metrics included colonic length, volume, tortuosity, and compactness and sigmoid apex height relative to the lumbosacral junction. Differences were measured using the Student's t test, and intra-reader reliability was assessed using ICC. The relative risk of incomplete rectosigmoid visualization was determined by reviewing the endoscopy reports. RESULTS: Women with hysterectomy had a lower sigmoid apex height (p = 0.002), as well as increased tortuosity (p = 0.012) and compactness (p = 0.001) and decreased length (p = 0.026) and volume (p = 0.016) of the rectosigmoid. Intra-reader reliability was high for centerline length (ICC = 0.9940) and sigmoid apex height (ICC = 0.9851). The relative risk of incomplete visualization of the rectosigmoid on endoscopy in women with hysterectomy was 2.068 (p = 0.043) compared to women without hysterectomy. CONCLUSION: Our pilot data show reproducible quantitative differences in three-dimensional metrics of the rectosigmoid in women with or without hysterectomy who underwent CTC for incomplete endoscopy and increased relative risk of incomplete endoscopic visualization of the rectosigmoid after hysterectomy. Our findings suggest that women with hysterectomy may benefit from CTC rather than endoscopy as the initial diagnostic test for evaluating the colon.

Computer-Aided Detection of Polyps in Optical Colonoscopy Images.

We present a computer-aided detection algorithm for polyps in optical colonoscopy images. Polyps are the precursors to colon cancer. In the US alone, more than 14 million optical colonoscopies are performed every year, mostly to screen for polyps. Optical colonoscopy has been shown to have an approximately 25% polyp miss rate due to the convoluted folds and bends present in the colon. In this work, we present an automatic detection algorithm to detect these polyps in the optical colonoscopy images. We use a machine learning algorithm to infer a depth map for a given optical colonoscopy image and then use a detailed pre-built polyp profile to detect and delineate the boundaries of polyps in this given image. We have achieved the best recall of 84.0% and the best specificity value of 83.4%.

Automated visibility map of the internal colon surface from colonoscopy video.

PURPOSE: Optical colonoscopy is a prominent procedure by which clinicians examine the surface of the colon for cancerous polyps using a flexible colonoscope. One of the main concerns regarding the quality of the colonoscopy is to ensure that the whole colonic surface has been inspected for abnormalities. In this paper, we aim at estimating areas that have not been covered thoroughly by providing a map from the internal colon surface. METHODS: Camera parameters were estimated using optical flow between consecutive colonoscopy frames. A cylinder model was fitted to the colon structure using 3D pseudo stereo vision and projected into each frame. A circumferential band from the cylinder was extracted to unroll the internal colon surface (band image). By registering these band images, drift in estimating camera motion could be reduced, and a visibility map of the colon surface could be generated, revealing uncovered areas by the colonoscope. Hidden areas behind haustral folds were ignored in this study. The method was validated on simulated and actual colonoscopy videos. The realistic simulated videos were generated using a colonoscopy simulator with known ground truth, and the actual colonoscopy videos were manually assessed by a clinical expert. RESULTS: The proposed method obtained a sensitivity and precision of 98 and 96 % for detecting the number of uncovered areas on simulated data, whereas validation on real videos showed a sensitivity and precision of 96 and 78 %, respectively. Error in camera motion drift could be reduced by almost 50 % using results from band image registration. CONCLUSION: Using a simple cylindrical model for the colon and reducing drift by registering band images allows for the generation of visibility maps. The current results also suggest that the provided feedback through the visibility map could enhance clinicians' awareness of uncovered areas, which in return could reduce the probability of missing polyps.

Complications of optical colonoscopy: CT findings.

The development of colorectal cancer screening programs in many countries has led to increasingly large numbers of patients undergoing optical colonoscopy. Although acute complications from screening optical colonoscopy are uncommon, they may occur in up to 5% or more of patients where biopsies or therapeutic procedures are performed. Abdominal radiographs are of value only for the detection of intraperitoneal perforation. There is a wide spectrum of other important associated complications. Such complications are most reliably identified using abdominal and pelvic CT, which also can guide appropriate conservative, interventional, or surgical management.

3D Reconstruction of virtual colon structures from colonoscopy images.

This paper presents the first fully automated reconstruction technique of 3D virtual colon segments from individual colonoscopy images. It is the basis of new software applications that may offer great benefits for improving quality of care for colonoscopy patients. For example, a 3D map of the areas inspected and uninspected during colonoscopy can be shown on request of the endoscopist during the procedure. The endoscopist may revisit the suggested uninspected areas to reduce the chance of missing polyps that reside in these areas. The percentage of the colon surface seen by the endoscopist can be used as a coarse objective indicator of the quality of the procedure. The derived virtual colon models can be stored for post-procedure training of new endoscopists to teach navigation techniques that result in a higher level of procedure quality. Our technique does not require a prior CT scan of the colon or any global positioning device. Our experiments on endoscopy images of an Olympus synthetic colon model reveal encouraging results with small average reconstruction errors (4.1 mm for the fold depths and 12.1 mm for the fold circumferences).

Computed tomography colonography for colorectal cancer screening.

Colorectal cancer screening has been shown to help prevent cancer-related death. Concerns about suboptimal adherence to conventional colonoscopy has led to the search for alternative screening modalities. Computed tomography colono-graphy (CTC) is a highly sensitive and minimally invasive alternative modality. The American College of Radiology has established a standardized reporting system for CTC. The advantages of CTC include complete colonic examination and extraluminal imaging in a single breath hold time. Lack of sensitivity in the evaluation of flat lesions and radiation exposure are the main concerns with this modality. Although the usefulness of CTC has been demonstrated in academic centers, larger studies in community settings are needed to facilitate its adoption by healthcare services.