Diminutive and Small Colorectal Polyps: The Pathologist's Perspective

Colorectal Polyp Image Detection and Classification through Grayscale Images and Deep Learning

Colonoscopy screening and colonoscopic polypectomy can decrease the incidence and mortality rate of colorectal cancer (CRC). The adenoma detection rate and accuracy of diagnosis of colorectal polyp which vary in different experienced endoscopists have impact on the colonoscopy protection effect of CRC. The work proposed a colorectal polyp image detection and classification system through grayscale images and deep learning. The system collected the data of CVC-Clinic and 1000 colorectal polyp images of Linkou Chang Gung Medical Hospital. The red-green-blue (RGB) images were transformed to 0 to 255 grayscale images. Polyp detection and classification were performed by convolutional neural network (CNN) model. Data for polyp detection was divided into five groups and tested by 5-fold validation. The accuracy of polyp detection was 95.1% for grayscale images which is higher than 94.1% for RGB and narrow-band images. The diagnostic accuracy, precision and recall rates were 82.8%, 82.5% and 95.2% for narrow-band images, respectively. The experimental results show that grayscale images achieve an equivalent or even higher accuracy of polyp detection than RGB images for lightweight computation. It is also found that the accuracy of polyp detection and classification is dramatically decrease when the size of polyp images small than 1600 pixels. It is recommended that clinicians could adjust the distance between the lens and polyps appropriately to enhance the system performance when conducting computer-assisted colorectal polyp analysis.

Virtual chromoendoscopy for the real-time assessment of colorectal polyps in vivo: a systematic review and economic evaluation

BACKGROUND

Current clinical practice is to remove a colorectal polyp detected during colonoscopy and determine whether it is an adenoma or hyperplastic by histopathology. Identifying adenomas is important because they may eventually become cancerous if untreated, whereas hyperplastic polyps do not usually develop into cancer, and a surveillance interval is set based on the number and size of adenomas found. Virtual chromoendoscopy (VCE) (an electronic endoscopic imaging technique) could be used by the endoscopist under strictly controlled conditions for real-time optical diagnosis of diminutive (≤ 5 mm) colorectal polyps to replace histopathological diagnosis.

OBJECTIVE

To assess the clinical effectiveness and cost-effectiveness of the VCE technologies narrow-band imaging (NBI), flexible spectral imaging colour enhancement (FICE) and i-scan for the characterisation and management of diminutive (≤ 5 mm) colorectal polyps using high-definition (HD) systems without magnification.

DESIGN

Systematic review and economic analysis.

PARTICIPANTS

People undergoing colonoscopy for screening or surveillance or to investigate symptoms suggestive of colorectal cancer.

INTERVENTIONS

NBI, FICE and i-scan.

MAIN OUTCOME MEASURES

Diagnostic accuracy, recommended surveillance intervals, health-related quality of life (HRQoL), adverse effects, incidence of colorectal cancer, mortality and cost-effectiveness of VCE compared with histopathology.

DATA SOURCES

Electronic bibliographic databases including MEDLINE, EMBASE, The Cochrane Library and Database of Abstracts of Reviews of Effects were searched for published English-language studies from inception to June 2016. Bibliographies of related papers, systematic reviews and company information were screened and experts were contacted to identify additional evidence.

REVIEW METHODS

Systematic reviews of test accuracy and economic evaluations were undertaken in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Meta-analyses were conducted, where possible, to inform the independent economic model. A cost-utility decision-analytic model was developed to estimate the cost-effectiveness of VCE compared with histopathology. The model used a decision tree for patients undergoing endoscopy, combined with estimates of long-term outcomes (e.g. incidence of colorectal cancer and subsequent morbidity and mortality) derived from University of Sheffield School of Health and Related Research's bowel cancer screening model. The model took a NHS perspective, with costs and benefits discounted at 3.5% over a lifetime horizon. There were limitations in the data on the distribution of adenomas across risk categories and recurrence rates post polypectomy.

RESULTS

Thirty test accuracy studies were included: 24 for NBI, five for i-scan and three for FICE (two studies assessed two interventions). Polyp assessments made with high confidence were associated with higher sensitivity and endoscopists experienced in VCE achieved better results than those without experience. Two economic evaluations were included. NBI, i-scan and FICE are cost-saving strategies compared with histopathology and the number of quality-adjusted life-years gained was similar for histopathology and VCE. The correct surveillance interval would be given to 95% of patients with NBI, 94% of patients with FICE and 97% of patients with i-scan.

LIMITATIONS

Limited evidence was available for i-scan and FICE and there was heterogeneity among the NBI studies. There is a lack of data on longer-term health outcomes of patients undergoing VCE for assessment of diminutive colorectal polyps.

CONCLUSIONS

VCE technologies, using HD systems without magnification, could potentially be used for the real-time assessment of diminutive colorectal polyps, if endoscopists have adequate experience and training.

FUTURE WORK

Future research priorities include head-to-head randomised controlled trials of all three VCE technologies; more research on the diagnostic accuracy of FICE and i-scan (when used without magnification); further studies evaluating the impact of endoscopist experience and training on outcomes; studies measuring adverse effects, HRQoL and anxiety; and longitudinal data on colorectal cancer incidence, HRQoL and mortality.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016037767.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Risk Factors of Advanced Adenoma in Small and Diminutive Colorectal Polyp

The aims of this study were to review the clinicopathological characteristics of diminutive (≤ 5 mm) and small polyps (> 5 mm but < 10 mm) and to evaluate the risk factors of advanced adenoma for polyps of diameter < 10 mm in the colon. The medical records of 4,711 patients who underwent first colonoscopy at outpatient clinics or health promotion center were reviewed retrospectively. We analyzed the presence and risk factors of advanced adenoma, which was defined as a villous or tubulovillous polyp, high-grade dysplasia or intramucosal carcinoma histologically. Total 5,058 polyps were detected in the 4,711 patients, and 93.0% (4,704/5,058) polyps were < 10 mm in size. Among them, advanced adenoma was noted in 0.6% (28/4,704) with a villous component in 19, high-grade dysplasia in 3, and adenocarcinoma in 6. Advanced and non-advanced adenomas differed significantly in age group, gender, and polyp size. Multivariate analysis showed that an advanced age (> 65 years), a male gender, and a polyp size of > 5 mm were risk factors of advanced adenoma. The incidence of advanced adenoma in polyps of < 10 mm was 0.6%. Polyp size, male gender, and age of > 65 years are independent risk factors of advanced adenoma.

International digestive endoscopy network 2014: turnpike to the future

Social networks are useful in the study of relationships between individuals or entire populations, and the ties through which any given social unit connects. Those represent the convergence of the various social contacts of that unit. Consequently, the term "social networking service" (SNS) became extremely familiar. Similar to familiar SNSs, International Digestive Endoscopy Network (IDEN) 2014 was based on an international network composed of an impressive 2-day scientific program dealing with a variety of topics for gastrointestinal (GI) diseases, which connects physicians and researchers from all over the world. The scientific programs included live endoscopic demonstrations and provided cutting-edge information and practice tips as well as the latest advances concerning upper GI, lower GI, and pancreatobiliary endoscopy. IDEN 2014 featured American Society for Gastrointestinal Endoscopy-Korean Society of Gastrointestinal Endoscopy (ASGE-KSGE)-joint sessions prepared through cooperation between ASGE and KSGE. Furthermore, IDEN 2014 provided a special program for young scientists called the 'Asian Young Endoscopist Award Forum' to foster networks, with many young endoscopists from Asian countries taking an active interest and participation.