Clinical Trial: High Definition Endoscopy With i-Scan for Small Colonic Polyp Evaluation: The HiScope Study

Study Status: Completed
Recruit Status: Completed
Study Type: Observational

Official Title: A Prospective Single-blind Observational Cohort Study of High Definition White Light Endoscopy and i-Scan Image Enhancement for the Characterisation of Small Colonic Polyps

Brief Summary:

Current standard practice is to remove all colonic polyps found during colonoscopy as it has not been possible to distinguish between polyps with some malignant potential (adenomatous) and those with negligable malignant potential (non-adenomatous).

Recent advances in endoscope imaging and technology have allowed endoscopists to distinguish between these two types of polyps by examining minute surface details.

i-Scan is a new digital enhancement method that aims to enhance surface details and may enable similar accurate distinction between adenomatous and non-adenomatous polyps.

Hypothesis:

High definition white light endoscopy plus i-Scan improves diagnostic accuracy of in-vivo assessment of colonic polyps <10mm in size over high definition white light endoscopy alone.

Detailed Summary:

Traditionally all polyps detected at colonoscopy, except obvious cancers, have been removed. It is felt that small (<10mm diameter) hyperplastic polyps cannot be reliably distinguished from adenomatous polyps by endoscopists [1]. Therefore a large number of hyperplastic polyps are removed unnecessarily. This results in increased risk to patients through exposing them to unnecessary polypectomy, and increased cost to the health service through the cost of processing greater numbers of histopathology specimens. The cost per specimen is around £58.

This challenge of distinguishing small hyperplastic polyps from small adenomatous polyps has been met over the past decade through the use of novel chromoendoscopy and computed 'virtual chromoendoscopy' techniques.

Chromoendoscopy involves using staining or contrast dyes to highlight the minute surface patterns in the mucosa of the gastrointestinal tract. The dyes are applied to the colonic mucosa via the working channels of the endoscope. Vital stains such as cresyl violet and methylene blue, which are taken up into epithelial cells, have been used by Japanese endoscopists for many years. Work by Kudo et al showed that by using these stains in combination with magnification endoscopy the minute 'pit patterns' of colonic mucosal lesions could be precisely examined and classified. The pits described are the surface opening of the mucosal crypts. Kudo showed that the surface pit pattern could predict the histology of a lesion with high accuracy [2-4], enabling distinction between adenomatous and hyperplastic polyps. Concerns regarding potential harmful effects of vital stains increased the popularity of an alternative chromoendoscopy dye, indigocarmine [5]. Indigocarmine is not taken up by cells but lies on the colonic wall. Studies from East Asia, the USA and Europe publishe
Sponsor: Portsmouth Hospitals NHS Trust

Current Primary Outcome: Diagnostic Accuracy of In-vivo Polyp Assessment [ Time Frame: Once histopathology results are known, approximately 2 weeks after in-vivo assessment ]

Original Primary Outcome: Diagnostic Accuracy of In-vivo Polyp Assessment [ Time Frame: Once histopathology results are known, approximately 2 weeks after in-vivo assessment ]

Current Secondary Outcome:

• Sensitivity for Adenomatous Histology of Colonic Polyps <10mm in Size [ Time Frame: Once histopathology results are known, approximately 2 weeks after in-vivo assessment ]
  Sensitivity for adenomatous histology of in-vivo assessment of colonic polyps <10mm in size using high definition white light endoscopy and high definition white light endoscopy plus i-Scan image enhancement. Sensitivity compared to the gold standard of histopathology. Senstivity for adenomatous histology = number of correctly identified adenomas (true positives)/total number of adenomas (true positives + false negatives)
• Specificity for Adenomatous Histology of Colonic Polyps <10mm in Size [ Time Frame: Once histopathology results are known, approximately 2 weeks after in-vivo assessment ]
  Specificity for adenomatous histology of in-vivo assessment of colonic polyps <10mm in size using high definition white light endoscopy and high definition white light endoscopy plus i-Scan image enhancement. Specificity compared to the gold standard of histopathology. Specificity for adenomatous histology = number of correctly identified non-neoplastic polyps (true negatives)/total number of non-neoplastic polyps (true negatives + false positives)
• Negative Predictive Value for Adenomatous Histology of Rectosigmoid Polyps ≤5mm in Size [ Time Frame: Once histopathology results are known, approximately 2 weeks after in-vivo assessment ]
  Negative predictive value for adenomatous histology of rectosigmoid polyps ≤5mm in size using high definition white light endoscopy and high definition white light endoscopy plus i-Scan image enhancement. NPV compared to the gold standard of histopathology. Negative predictive value = number of true negatives/(number of true negatives + number of false negatives)

Original Secondary Outcome:

• Sensitivity for Adenomatous Histology of Colonic Polyps <10mm in Size [ Time Frame: Once histopathology results are known, approximately 2 weeks after in-vivo assessment ]
  Sensitivity for adenomatous histology of in-vivo assessment of colonic polyps <10mm in size using high definition white light endoscopy and high definition white light endoscopy plus i-Scan image enhancement. Sensitivity compared to the gold standard of histopathology.
• Specificity for Adenomatous Histology of Colonic Polyps <10mm in Size [ Time Frame: Once histopathology results are known, approximately 2 weeks after in-vivo assessment ]
  Specificity for adenomatous histology of in-vivo assessment of colonic polyps <10mm in size using high definition white light endoscopy and high definition white light endoscopy plus i-Scan image enhancement. Specificity compared to the gold standard of histopathology.
• Negative Predictive Value for Adenomatous Histology of Rectosigmoid Polyps ≤5mm in Size [ Time Frame: Once histopathology results are known, approximately 2 weeks after in-vivo assessment ]
  Negative predictive value for adenomatous histology of rectosigmoid polyps ≤5mm in size using high definition white light endoscopy and high definition white light endoscopy plus i-Scan image enhancement. NPV compared to the gold standard of histopathology.

Dates:
Date Received: January 3, 2013
Date Started: May 2011
Date Completion:
Last Updated: February 25, 2013
Last Verified: February 2013