Advanced endoscopic imaging in the gastrointestinal tract: improving the view of Neoplasia
Student thesis: Doctoral Thesis
Gastrointestinal endoscopy is a vital tool for the detection and treatment of early neoplasia in the upper and lower gastrointestinal tracts. Survival from gastrointestinal cancer is largely dependent on the stage at diagnosis – thus detection of early lesions, or better still treatment of pre-cancerous lesions is vital to improve outcomes. The world of endoscopy is changing rapidly with the development of dye-based and digital enhancement techniques with the aim of improving the detection and characterisation of neoplastic lesions. This thesis reviews the development of all the main advanced imaging techniques and comprehensively reviews the evidence for the use of these in the colon. Chapter 4 describes the development of a new classification system for characterising small colonic polyps using the Pentax i-Scan digital enhancement system. Chapter 5 describes a prospective cohort study using i-Scan for the in-vivo characterisation of small colonic polyps in 87 patients. No differences in the accuracy of polyp characterisation between high-definition white light endoscopy, i-Scan and chromoendoscopy were found when performed by an expert endoscopist. All 3 modalities met the ASGE criteria for management based on optical diagnosis. Chapter 7 describes a randomised controlled clinical trial recruiting 126 patients of a pre-endoscopy drink containing water, n-acetyl cysteine and simeticone. This was shown to significantly improve mucosal visibility compared to water alone, or no preparation, and also significantly reduced the need for procedural fluid flushes. Chapter 6 describes a retrospective study looking at factors influencing polyp and adenoma detection in a large UK Bowel cancer screening cohort. Endoscope definition (standard vs high definition) was examined in particular. In this group of patients, endoscope definition was found to have no impact on any outcome measure, but endoscopist and bowel preparation were consistent predictors of key quality outcomes. Chapter 7 describes a randomised controlled clinical trial recruiting 126 patients of a pre-endoscopy drink containing water, n-acetyl cysteine and simeticone. This was shown to significantly improve mucosal visibility compared to water alone, or no preparation, and also significantly reduced the need for procedural fluid flushes. Chapters 8 & 9 describes two studies examining the baseline performance and impact of training modules on the accuracy of colonic lesion and polyp characterisation amongst non-endoscopists and endoscopists with varying degrees of experience. Baseline performance of experienced endoscopists was found to be no different to that of inexperienced endoscopists and novices in both studies, but training improved accuracy in all groups. These studies highlight the need for training in lesion characterisation to become part of the formal training programme for all endoscopists.
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