A robust method to track colonoscopy videos with non-informative images

PURPOSE

Continuously, optical and virtual image alignment can significantly supplement the clinical value of colonoscopy. However, the co-alignment process is frequently interrupted by non-informative images. A video tracking framework to continuously track optical colonoscopy images was developed and tested.

METHODS

A video tracking framework with immunity to non-informative images was developed with three essential components: temporal volume flow, region flow, and incremental egomotion estimation. Temporal volume flow selects two similar images interrupted by non-informative images; region flow measures large visual motion between selected images; and incremental egomotion processing estimates significant camera motion by decomposing each large visual motion vector into a sequence of small optical flow vectors. The framework was extensively evaluated via phantom and colonoscopy image sequences. We constructed two colon-like phantoms, a straight phantom and a curved phantom, to measure actual colonoscopy motion.

RESULTS

In the straight phantom, after 48 frames were excluded, the tracking error was [Formula: see text]3 mm of 16 mm traveled. In the curved phantom, the error was [Formula: see text]4 mm of 23.88 mm traveled after 72 frames were excluded. Through evaluations with clinical sequences, the robustness of the tracking framework was demonstrated on 30 colonoscopy image sequences from 22 different patients. Four specific sequences among these were chosen to illustrate the algorithm's decreased sensitivity to (1) fluid immersion, (2) wall contact, (3) surgery-induced colon deformation, and (4) multiple non-informative image sequences.

CONCLUSION

A robust tracking framework for real-time colonoscopy was developed that facilitates continuous alignment of optical and virtual images, immune to non-informative images that enter the video stream. The system was validated in phantom testing and achieved success with clinical image sequences.

Effectiveness of a simplified "patient friendly" split dose polyethylene glycol colonoscopy prep in Veterans Health Administration patients

BACKGROUND AND OBJECTIVES

Adequate colon cleansing is an important factor in performing quality colonoscopy. Split dose Polyethylene Glycol (PEG) solutions have been shown to improve colon cleansing, but the effectiveness in a large clinical practice of elderly co-morbid patients has not been demonstrated. The aim of this study was to assess the efficacy of a simplified split PEG bowel prep in Veterans Health Administration (VHA) patients.

METHODS

Prospective pre-post study design of VHA patients undergoing routine colonoscopy. Bowel prep quality was assessed using a standardized semi-quantitative 5-point scale. "Standard" 4L PEG prep was consumed once the evening before the procedure. "Split" prep was consumed half in the early evening and half in the late evening or early morning depending on procedure time.

RESULTS

Right colon preps were Excellent/Good in 81.4% of split preps (n=199) vs. 63% of standard preps (n=447, p<0.001). Left colon preps were Excellent/Good in 85.9% of split preps vs. 71.6% of standard preps (p<0.001). Diabetics (n=133) had significantly more right colon preps rated fair or worse compared to non-diabetics irrespective of prep (39.9% vs. 29.0%, p=0.02). Split prep in diabetics resulted in fewer right colon preps rated fair or worse compared to diabetics using standard prep (28.3% vs. 45.9%, p=0.049). Average adenomas detected per colonoscopy were 1.04 for split prep vs. 0.85 for standard prep (p=NS). Patient satisfaction was higher for split preps.

CONCLUSION

System-wide implementation of a split PEG prep resulted in significantly improved bowel cleansing in VHA patients, particularly in the right colon. Improved bowel cleansing with split preps was associated with higher patient satisfaction.

Screening of de novo tumors after liver transplantation

De novo malignancies are frequent complications after liver transplantation. They are one of the leading causes of late death. Some authors have reported promising results following implementation of extensive cancer surveillance programs. Screening protocols might benefit patients by providing a diagnosis at an earlier stage when tumors may be cured. These protocols should be based on the specific risk factors of every patient. Unfortunately, the scientific evidence supporting screening protocols is still very weak both in the general population and in the transplant patients. On this basis, there is not enough evidence to recommend routine screening for all liver transplant recipients, apart from the recommendations accepted for the general population. Multicenter studies in selected groups of patients at high risk for malignancy may be the only way of defining the potential benefit of screening programs post-transplantation.

Is production pressure jeopardizing the quality of colonoscopy? A survey of U.S. endoscopists' practices and perceptions

BACKGROUND

Fatigue is an underestimated cause of underperformance among physicians. There is evidence that fatigue or other byproducts of production pressure may negatively influence the quality of colonoscopy.

OBJECTIVE

To investigate the practices and perceptions of U.S. endoscopists regarding the effect of production pressure on the performance of colonoscopy.

DESIGN

We conducted a 40-question online survey to assess endoscopists' practices and perceptions concerning production pressure.

SETTING

A total of 5030 U.S. American Society for Gastrointestinal Endoscopy members.

MAIN OUTCOME MEASUREMENTS

The proportion of endoscopists responding positively to questions pertaining to the impact of production pressure on colonoscopy practice.

RESULTS

Ninety-two percent of respondents indicated that production pressure influenced one or more aspects of their endoscopic practices. Examples of production pressure included (1) postponing polypectomy for a subsequent session (2.8%), (2) reducing the length of time spent inspecting the colon (7.2%), and (3) proceeding with colonoscopy in a patient with an unfavorable risk/benefit ratio (69.2%). Forty-eight percent of respondents reported witnessing the effects of production pressure on a colleague. Respondents working fee-for-service and those with >10 years since completion of fellowship were more likely to describe their weekly workloads as excessive compared with those who were salaried (81.3% vs 71.3%; P = .01) and <10 years out of training (81% vs 72.7%; P = .01).

LIMITATIONS

Nonresponse bias due to low response rate (22.3%).

CONCLUSION

Production pressure influences the conduct of colonoscopy for many endoscopists and could have an adverse effect on the outcome of colorectal cancer screening. (

CLINICAL TRIAL REGISTRATION NUMBER

RE:GIE D 11-01288R1.) The study was an Internet study and did not involve human subjects.

Managed care and the diffusion of endoscopy in fee-for-service Medicare

OBJECTIVE

To determine whether Medicare managed care penetration impacted the diffusion of endoscopy services (sigmoidoscopy, colonoscopy) among the fee-for-service (FFS) Medicare population during 2001-2006.

METHODS

We model utilization rates for colonoscopy or sigmoidoscopy as impacted by both market supply and demand factors. We use spatial regression to perform ecological analysis of county-area utilization rates over two time intervals (2001-2003, 2004-2006) following Medicare benefits expansion in 2001 to cover colonoscopy for persons of average risk. We examine each technology in separate cross-sectional regressions estimated over early and later periods to assess differential effects on diffusion over time. We discuss selection factors in managed care markets and how failure to control perfectly for market selection might impact our managed care spillover estimates.

RESULTS

Areas with worse socioeconomic conditions have lower utilization rates, especially for colonoscopy. Holding constant statistically the socioeconomic factors, we find that managed care spillover effects onto FFS Medicare utilization rates are negative for colonoscopy and positive for sigmoidoscopy. The spatial lag estimates are conservative and interpreted as a lower bound on true effects. Our findings suggest that managed care presence fostered persistence of the older technology during a time when it was rapidly being replaced by the newer technology.

Assessing the impact of screening colonoscopy on mortality in the medicare population

BACKGROUND

Some have recommended against routine screening for colorectal cancer (CRC) among patients ≥75 years of age, while others have suggested that screening colonoscopy (SC) is less beneficial for women than men. We estimated the expected benefits (decreased mortality from CRC) and harms (SC-related mortality) of SC based on sex, age, and comorbidity.

OBJECTIVE

To stratify older patients according to expected benefits and harms of SC based on sex, age, and comorbidity.

DESIGN

Retrospective study using Medicare claims data.

PARTICIPANTS

Medicare beneficiaries 67-94 years old with and without CRC.

MAIN MEASURES

Life expectancy, CRC- and colonoscopy-attributable mortality rates across strata of sex, age, and comorbidity, pay-off time (i.e. the minimum time until benefits from SC exceeded harms), and life-years saved for every 100,000 SC.

KEY RESULTS

Increasing age and comorbidity were associated with lower CRC-attributable mortality. Due to shorter life expectancy and CRC-attributable mortality, the benefits associated with SC were substantially lower among patients with greater comorbidity. Among men aged 75-79 years with no comorbidity, the number of life-years saved was 459 per 100,000 SC, while men aged 67-69 with ≥3 comorbidities had 81 life-years saved per 100,000 SC. There was no evidence that SC was less effective in women. Among men and women 75-79 with no comorbidity, number of life-years saved was 459 and 509 per 100,000 SC, respectively; among patients with ≥3 comorbidities, there was no benefit for either men or women.

CONCLUSIONS

Although the effectiveness of SC was equivalent for men and women, there was substantial variation in SC effectiveness within age groups, arguing against screening recommendations based solely on age.

User's perspectives of barriers and facilitators to implementing quality colonoscopy services in Canada: a study protocol

BACKGROUND

Colorectal cancer (CRC) represents a serious and growing health problem in Canada. Colonoscopy is used for screening and diagnosis of symptomatic or high CRC risk individuals. Although a number of countries are now implementing quality colonoscopy services, knowledge synthesis of barriers and facilitators perceived by healthcare professionals and patients during implementation has not been carried out. In addition, the perspectives of various stakeholders towards the implementation of quality colonoscopy services and the need of an efficient organisation of such services have been reported in the literature but have not been synthesised yet. The present study aims to produce a comprehensive synthesis of actual knowledge on the barriers and facilitators perceived by all stakeholders to the implementation of quality colonoscopy services in Canada.

METHODS

First, we will conduct a comprehensive review of the scientific literature and other published documentation on the barriers and facilitators to implementing quality colonoscopy services. Standardised literature searches and data extraction methods will be used. The quality of the studies and their relevance to informing decisions on colonoscopy services implementation will be assessed. For each group of users identified, barriers and facilitators will be categorised and compiled using narrative synthesis and meta-analytical techniques. The principle factors identified for each group of users will then be validated for its applicability to various Canadian contexts using the Delphi study method. Following this study, a set of strategies will be identified to inform decision makers involved in the implementation of quality colonoscopy services across Canadian jurisdictions.

DISCUSSION

This study will be the first to systematically summarise the barriers and facilitators to implementation of quality colonoscopy services perceived by different groups and to consider the local contexts in order to ensure the applicability of this knowledge to the particular realities of various Canadian jurisdictions. Linkages with strategic partners and decision makers in the realisation of this project will favour the utilisation of its results to support strategies for implementing quality colonoscopy services and CRC screening programs in the Canadian health system.

Population-based screening for colorectal cancer with faecal occult blood test--do we really have enough evidence?

INTRODUCTION

Population-based randomised controlled trials (RCT) have shown that invitation to biennial screening with faecal occult blood testing (FOBT) during 10 or more years reduced colorectal cancer-specific mortality. These results have stimulated plans to introduce mass screening in various countries; however, none of these trials has been able to show any reduction of total mortality, which should be expected with reduced disease-specific mortality in a RCT.

METHODS

The aim of this review is to analyse, in more detail, the findings in these trials. The results of the trials have, in this review, been systematised and discussed in the context of potential bias, validity and effectiveness.

RESULTS

It is found that the reduced cancer-specific mortality is modest and that the clinical significance may be discussed. The number of persons needed to be invited for multiple screening rounds to avoid one death in colorectal cancer (CRC) is high, ranging from about 600 to 1,200. A remarkable finding is that only one fourth of the carcinomas in those invited to the screening were actually detected by this intervention. The absence of reduced total mortality in all series is a serious problem and evokes questions about the validity in determination of cause of death. None of these trials showed any effect on incidence of CRC by removal of precancerous adenomas.

CONCLUSIONS

It seems reasonable to conclude that the scientific evidence to support introduction of population-based screening programmes with FOBT appears not yet strong enough. In addition, harm/benefit and cost/effectiveness ratios are not well determined.

Efficacy and effectiveness of colonoscopy: how do we bridge the gap?

Colonoscopy is sometimes considered the preferred colorectal cancer screening modality, yet this modality may be subject to variation in operator performance more than any other screening test. Failures of colonoscopy to consistently detect precancerous lesions threaten the effectiveness of this technique for the prevention of colorectal cancer. Studies on high-level adenoma detectors under optimal conditions have begun to establish the true efficacy of colonoscopy and further widen the gap between efficacy and effectiveness. Research is required to establish the component skills, attitudes, and behaviors for high-level mucosal inspection competence necessary for training and assessment. Interventions to bridge the gap between efficacy and effectiveness are lacking, yet they should emphasize quality measurement and operate at various levels within the health system to motivate change in endoscopist behavior.

The dimensions of the CRC problem

Colorectal cancer is a significant health problem, the importance of which will increase substantially in the coming years, both in more, as well as in less developed regions of the world. The present paper describes the dimensions of the problem from an epidemiologic viewpoint as well as from the perspective of policy makers and professionals seeking to control the disease. Currently, colorectal cancer is the third most common cancer and the fourth most common cause of cancer deaths worldwide, with 1.2 million estimated cases and 609,000 estimated deaths in 2008. Based on demographic trends, the annual incidence is expected to increase by nearly 80% to 2.2 million cases over the next two decades and most of this increase will occur in the less developed regions of the world (62%). These regions are ill equipped to deal with the rapidly increasing demand for cancer treatment resulting from population growth and higher life expectancy. Concerted efforts to control colorectal cancer are therefore of great importance worldwide. They will require allocation of additional resources and should be based on an appropriate balance between prevention, diagnosis and treatment.